CA1314100C - Managing data storage space on large capacity record media - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A large capacity data storing disk includes a volume table of contents (VTOC) which identifies allocated ones of data storage tracks and identification of the data contents therein, indications of unallocated data storage track and an indication of which of the data storage tracks on the large capacity disk surface are unformatted. The indica-tions may also include indications of unallocated "erased"
tracks that do not contain data residuals from previous recordings. Those unallocated tracks having such erased condition in a count key data record format (CKD) require a home address record on each of the formatted tracks. The home address record may include indications of rotational position of defects to be skipped over during the recording and readback operations. A specific embodiment of the invention using a magnetooptic record medium is described.

Description

MANAGING DATA STORAGE SPACE ON LARGE
CAPACITY RECORD MEDIA
Background of the Invention Field of the Invention The present invention relates to data storage and record media each having an extremely large data storing capacity, particularly apparatus and methods for employing such media in a user data processing or other information handling environment.
Description of the Prior Art Rewritable or erasable media have been used for years for recording all forms of information-bearing signals. In data processing environments, such media should exhibit low error rates for ensuring data integrity and rapid storage and recovery of data.
Typically, rewritable or erasable media have been of the magnetic recording type. Such magnetic media has taken the form of magnetic tapes, magnetic disks (direct access storage devices -- DASD) and magnetic drums. When such disk media are first used in a recording environment, each medium has to be initialized for recording, including formatting. Such formatting, depending upon the environment, may include an extensive surface analysis with the recording of control information in various addressable data storage areas of the record medium. Typically, in large capacity magnetic storage disks, such a control record is often called a home address record as set forth on pages 73 and 74 of a publication by Bohl, entitled "Introduction To IBM Direct Access Storage Devices", published by Science Research Associates, Inc., copyright 1981. Such initialization and surface analysis results in identification of the location of media defects. Then the locations and extents of such media defects are recorded in the home address area.
This arrangement allows a recorder to skip over the identified defects. Such arrangements, improve the yield of magnetic media and, thereforel greatly reduce the cost.
Another example of magnetic disk initialization is the formatting of the so-called flexible diskettes used on today's personal computers. Such diskettes are often referred to as being "soft sectored". To enable the personal computer to record and read data on and from such diskettes, a format operation by the personal computer does a surface analysis for identifying unrecordable areas on the diskette and for recording control indicia on the diskette for enabling the recording oeprations.
A problem arises for a user or customer of such media when the media data storing capacity becomes extremely large, 1 such as in the gigabyte range. Then the time required for

2 such soft sectoring and initialization may become oppres-

3 sive. Accordingly, a better solution to the present day

4 soft sectoring and media initialization is desired.

6 The above referred to magnetic disk media can be overwritten 7 without first erasing the previous contents. In some 8 magnetic media, such as many magnetic tapes, such overwrit-9 ing was usually preceded by an erasing step. In the magnet-ic tape situation, where erasure is first provided, the 11 procedure of so-called "updating data records in place" is 12 not permitted. As a result, magnetic tape was usually 13 written from the beginning of the tape to the end of the 14 tape in one pass for the above stated reason and other operating parameters beyond the scope of the present de-16 scription.

18 Optical recording media has almost an order of magnitude 19 greater data capacity for a given sized recording area than the current day magnetic recording media. Many current day 21 optical media are hard sectored, i.e., the sector marks are 22 molded into the media before shipment from a media factory.
23 Such molding occupies media space which could be used for 24 data storage. Also such media to date has been write once/read many (WORM). On the other hand, magnetooptic 26 media is rewritable but currently requires that the previous 27 recordings be erased before new data is recorded in any 28 given data storing area. Therefore, to update a data record 29 recorded on a magnetooptic medium requires a first scan of the record area for erasing the previously recorded data, a 1 second scan over the record area to record the updated 2 version of the data and when write or record verification is 3 required or desired a third scan for reading the just 4 recorded updated data. For magnetooptic disk media, a complete rotation of the disk is required between the erase 6 scan and the write scan resulting in a relatively low 7 performance magnetooptic recorder. While a separate erase 8 head and a separate write head could be provided on two 9 different actuators, the attendant cost could make magneto-optic recorders noncompetitive. Accordingly, it is desired 11 to provide better control procedures for using magnetooptic 12 media in information-bearing signal recorders. Such erase-13 before-record requirements also presently exist in the 14 so-called phase-change optical disks wherein the recording is represented by the material phases of amorphous and 16 crystalline states.

18 Optical media, including magnetooptic and phase change, are 19 currently subject to many media defects. Since the record-ing density per unit area is much higher, the sensitivity of 21 the recording to small defects becomes pronounced. Accord-22 ingly, such optical media even though being of a high 23 quality, exhibits a high error rate because of the small 24 areas of the media surface employed for recording 2S information-bearing signals.

27 When such media are employed for use in a data processing 28 environment, a most efficient use of the media is provided 29 by the so-called "count key data" format as described in Bohl supra, on page 27 and pages 73-75. Another format .,_~. . .. ~ . .

1 commonly used in recording information-bearing signals is 2 the fixed block architecture format which arbitrarily 3 divides the disk surface into addressable areas containing a 4 fixed number of recorded signals such as 2R, 4K bytes per addressable area. Such formatting requires identification 6 of all of the fixed bytes areas. The fixed block architec-7 ture is referred to and described on pages 27-28, 82-84 and 8 125 and 126 of the Bohl book supra. Such fixed block 9 architecture is often found on lower performing data pro-cessing environments, such as in the personal computer 11 environment.

13 A significant difference between the CKD and the fixed block 14 architecture is that the CRD format uses only an index mark for each of the record tracks on a disk plus a home address 16 area and count fields as referred to above. The record size 17 is variable such that the data records are recorded as units 18 of contiguous signals not dissected and distributed into a 19 group of fixed block-size sectors. Further, when recording a large number of small records in CKD, a relatively large 21 number of control signals are associated with such small 22 records; still all of the data storage space can be used for 23 the data and the control records rather than leaving unre-24 corded areas as found in fixed block architecture. Accord-ingly, means are desired for effectively using the CKD
26 format on optical disks in an efficient and low cost manner.
27 Such efficient use may require the interactivity between a 28 control unit and a recorder and in some circumstances, 29 interactive operation between a host processor, a control unit and a recorder.

~, . . . . . . . . . .. .... . .

1 Summary of the Invention 3 In accordance with the present invention, a record medium 4 having a multiplicity of addressable record tracks is received unformatted and not surface analyzed (unprocessed, 6 herein termed "new") in a user environment. Each of the new 7 record tracks has an index for indicating its beginning 8 point. In the user environment, a first initialization of 9 the record medium for signal recording includes the steps of surface analvzing a selected subset consisting of a prede-11 termined number of said new record tracks with the prede-12 termined number being substantiallv less than the total 13 number of tracks on the record medium. The detected surface 14 defects are indicated and identified by location and extent.
The surface analyzed tracks are then formatted. In such 16 formatting, the indication is recorded in a so-called home 17 address area of each of the surface analyzed tracks which 18 includes recording indications of the track positions and 19 extent of the surface defects. Such formatted record tracks can now receive and store data.

22 A volume table of contents (VTOC) recorded in one or more of 23 said record tracks includes identification of which tracks 24 Of the disk are in the surface analyzed and formatted sets;
which tracks are yet unformatted and not surface analvzed.
26 When a record medium is hard sectored, the individual 27 addressable sectors can be demarked with alternate sectors 28 being assigned to receive the data.

.,,, . , . . -- -. .. .. ... ..

1 As the record medium is used, the VTOC is updated for 2 indicating which of the tracks in the set are allocated for 3 data storage and which are free and available for alloca-4 tion. When the record med~um is not being used for record-ing signals thereon or reading signals therefrom, additional 6 ones of the new tracks are surface analyzed "in-line" and 7 identified in VTOC as being available for formatting. Once 8 formatted, such tracks are available for data recording.
9 This in-line surface analysis and formatting is repeated until all of the record tracks in the record medium have 11 been surface analyzed and formatted. The term "in-line"
12 means that media formatting and surface analysis is automat-13 ically interleaved between day-to-day data processing 14 operations.
16 When a record medium requires erasure of previously recorded 17 data before new data is recorded, the VTOC includes indica-18 tions of which tracks are unallocated and have been erased, 19 i.e., ready to receive data, and which tracks are unallocat-ed but not yet erased. When the record medium is not being 21 used for recording data or for reading data, then the 22 unallocated, not-yet-erased tracks are erased "in-line" for 23 making them more readily available for data recording., In a 24 specific aspect of the invention, whenever the record medium has used but unallocated tracks that are not yet erased, all 26 erasure procedures are completed before additional ones of 27 the new record tracks are surface analvzed and then format-Z8 ted.

TU987011 _7_ 1 31 4 ~ 00 1 A host processor employing the record medium for data 2 storage can determine that a sequential data set is being 3 recorded and that the recording can be applied to any of the 4 unallocated and erased record tracks rather than to the record tracks previously storing such a sequential data set.
6 This procedure eliminates the erasure step to be interleaved 7 between the request for recording and the actual recording.

g The foregoing and other objects, features, and advantages of the invention will be apparerlt from the following more 11 particular description of preferred embodiments of the 12 invention, as illustrated in the accompanying drawings.

14 Description of the Drawing 16 Fig. 1 diagrammatically illustrates a record medium using 17 the present invention.

19 Fig. 2 is a block diagram showing a recorder of the magneto-optic type which employs the Fig. 1 illustrated record 21 medium 23 Fig. 3 is a simplified block diagram of a host processor and 24 control unit connected to the Fig. 2-illustrated recorder.

26 Fig. 4 is a machine operations chart of a host processor 27 connected to the control unit of Fig. 3 showing those space 28 management machine operations used to employ the present 29 invention.

~ . .. , . . ~

~ 3 1 4 1 00 1 Fig. 5 is a simplified machine operations chart for the host 2 processor for enabling certain recording operations.
4 Detailed Description 6 Referring now more particularly to the drawing, like numer-7 als indicate like parts and structural features in the 8 various figures. As usual, magnetooptic disk 30 has a 9 volume table of contents (VTOC) 10 recorded in the radially-outermost track of the disk. The addresses of the concen-11 tric tracks ~not shown) in data area 13 on disk 30 begin 12 with the lowest address track as the radially-outwardmost 13 track and increasing addresses to the radially-inwardmost 14 track. Disk 30 has a single radially-extending index line 11 which signifies the beginning of the recording area for 16 each of the record tracks of disk 30. In the initial area 17 of each record track is a home address area HA 12. Such 18 record tracks can be concentric separate tracks, convolu-19 tions of a single spiral track, logical tracks superposed on other physical indicia, etc.

22 VTOC 10, in accordance with the present invention, includes 23 four recorded areas identified space utilization of record-24 ing area 13. It is to be appreciated that VTOC 10 includes other information than that described for practicing the 26 present invention. In a first VTOC area 14, all of the 27 record tracks of disk 30 that are currently allocated for 28 storing information-bearing or data signals are identified.
29 Such identification can bq hy the physical addresæ referred to above, can be a directory which allows indirect ... - ... . . , . . , . , .. .~ , . . . , .. ~ . ..........

1 addres~ing from a logical address base to the physical 2 address base or other form of indication. A second VTOC
3 area 15 identifies the physical addresses of the free and 4 erased record tracks of disk 30. Such free and erased record tracks are unallocated for data storage but have been 6 erased, as will become apparent, and therefore, are ready to 7 receive data signals for recording. A third VTOC section 16 8 identifies the free (unallocated) tracks that are not yet g erased. Such free tracks are identified by the physical addresses are those that were previously recorded into and 11 have been deallocated from storing data. Therefore the 12 free, not erased tracks are available for allocation but are 13 not yet ready to receive recorded information in those disks 14 30 that require erasure of previously-recorded data before new data can be recorded. When a disk 30 has the capability 16 of overwriting recorded data, then the third VTOC section 16 17 may be dispensed with. A fourth VTOC area 17 identifies the 18 radially-outwardmost ones of the new non-analyzed plus the 19 surface-analyzed but unformatted record tracks. The format-ted record tracks have a HA record recorded therein (as 21 later described) whereas the unformatted tracks have been 22 surface analyzed but have no home address record recorded 23 therein. The new tracks have not yet been surface analyzed.

In a preferred embodiment of the invention, the shaded area 26 of HA 12 represents a radially outward and abbreviated set 27 of record tracks initially formatted for receiving data 28 signals for storage; thence indicated in first VTOC section 29 14. The fourth VTOC area 17 identifies the radial track of disk 30 which is a next radially inward track that has not .. . , , , .~ .. ... ~ ..

1 been surface anal~zed plus the radially-outermost track that 2 was surface analvzed but not yet formatted.

4 The space management of disk 30 can be performed in a host processor attaching a data storage system having a later-6 described programmable control unit. Such programmed space 7 management needs information stored in VTOC 10 for the space 8 management functions. The space management functions may be 9 performed in the programmable control unit instead of a host processor. In either event, the machine operations perform 11 the same functions as later set forth. The term "space 12 management" means either a host processor or control unit 13 executing computer programs for performing the machine 14 operations shown in Figs. 4 and 5. As shown in Fig. 3, the host processor has the space management.

17 For improving performance, a portion of VTOC 10 is inserted 18 into later-described program space status table (SST) 20.
19 SST 20 is created from VTOC 10 each time the recorder is powered on, reset, etc. SST 20 has four portions corre-21 sponding to the four VTOC areas 14-17. "Allocated" field 21 22 of SST 20 contains a subset of VTOC area 14. The SST 20 23 stored "allocated" information can be the total number of 24 allocated tracks of disk 30, and identification of a prede-termined set of the last referenced ones of the allocated 26 set of tracks. For example, up to fifty of the allocated 27 tracks can be identified in field 21. Similarl~, the free 28 and erased tracks identified in second VTOC portion 15 have 29 some of their addresses recorded in field 22 of SST 20. For example, the twenty radially-outwardmost ones of the free .. .. _ 1 31 4~l 00 1 and erased tracks may be identified in SST 20. In an 2 alternate arrangement, the free and erased tracks that have 3 an address affinity to the allocated tracks identified in 4 field 21 can be listed in field 22. Such affinity is the radial proximity of the free and erased tracks to the 6 allocated tracks last referenced. A third SST 20 field 23 7 identifies the free but not erased tracks. Such free but 8 not erased tracks are preferably a radially-outwardmost set g of the free and erased tracks for enabling a quick examina-tion of which tracks can be next erased. Also the total 11 number of ,ree and erased tracks and the free but not erased 12 tracks are respectively stored in fields 22 and 23. Such 13 numbers can also be used for analysis of the disk 30 usage.
14 Finally, in SST 20, field 24 contains the physical addresses of the radially-outwardmost one of the raw, not su-face-16 analyzed and unformatted tracks of disk 30. Such informa-17 tion may be used for load balancing and other purposes as 18 may be devised in a data processing environment.

An optical recorder with which the present invention mav be 21 advantageously employed is shown in Fig. 2. A magnetooptic 22 record disk 30 is mounted for rotation on sp-ndle 31 by 23 motor 32. Optical head-carrying ~rm 33 on head arm car-24 riage, generally dennted bv numeral 3a, moves radially of disk 30. A frame 35 of the recorder suitably mounts car-26 riage 34 for reciprocating radial motions. The radial 27 motions of carriage 34 enable access to anvone of a plurali-28 ty of concentric tracks or circumvolutions of a spiral track 29 for recording and recovering data on and from the disk.
Linear actuator 36 suitably mounted on frame 35, radially O

1 moves carriage 34 for enabling the track accessing. The 2 recorder is suitably attached to one or more host processors 3 37, such host processors may be control units, personal 4 computers, large system computers, communication systems, image process processors, and the like. Attaching circuits 6 38 provide the logical and electrical connections between 7 the optical recorder and the attaching host processors 37.

9 Microprocessor 40 controls the recorder including the attachment to the host processor 37. Control data, status 11 data, commands and the like are exchanged between attaching 12 circuits 38 and microprocessor 40 via bidirectional bus 43.
13 Included in microprocessor 40 is a program or microcode 14 storing, read-only memory tRO~.) 41 and a data and control signal storing random access memory (RAM) 42.

17 The optics of the recorder include an objective or focussing 18 lens 45 mounted for focussing and tracking motions on head 19 arm 33 by fine actuator 46. This actuator includes mecha-nisms for moving lens 45 toward and away from disk 30 for 21 focussing and track following and seeking movements radiallv 22 of disk 30; for example, for changing tracks within a range 23 of lO0 tracks so that carr~age 34 need not be actuated each 24 time a track adjacent to a track currently being accessed is to be accessed. Numeral 47 denotes the two-wav light path 26 between lens 45 and disk 30.

28 In magnetooptic recording, magnet 48 provides a weak mag-29 netic steering field for directing the remnant magnetization direction of a small spot on disk 30 illuminated by laser 1 light from lens 45. The laser light spot heats the illumi-2 nate spot on the record disk to a temperature above the 3 Curie point of the magnetooptic layer (not shown, but can be 4 an alloy of rare earth and transitional metals as taught by Chaudhari et al., US patent 3,949,387). This heating 6 enables magnet 48 to direct the remnant magnetization to a 7 desired direction of magnetization as the spot cools below 8 the Curie point temperature. Magnet 48 is shown as oriented 9 in the "write" direction, i.e., binary ones are recorded on disk 30 normally are "north pole remnant magnetization". To 11 erase disk 30, magnet 48 rotates so the south pole is 12 adjacent disk 30. Magnet 48 control 49 which is mechanic-13 ally coupled to rotatable magnet 48 as indicated by dashed 14 line 50, controls the write and erase directions. Micropro-cessor 40 supplies control signals over line 51 to control 16 49 for effecting reversal of the recording direction.

18 It is necessarv to control the radial position of the beam 19 following path 47 such that a track or circumvolution is faithfully followed and that a desired track or circum-21 volution is quickly and preciselv accessed. To this end, 22 focus and tracking circuits 54 control both the coarse 23 actuator 36 and fine actuator 46. The positioning of car-24 riage 34 by actuator 36 is precisely controlled by control signals supplied by circuits 54 over line 55 to actuator 36.
26 Additionally, the actuator control by circults 54 is exer-27 cised by control signals travelling over lines 57 and 58 28 respectively for focus and fine tracking and switching 29 actions of fine actuator 46. Various servo positioning controls may be successfully emploved.

1 The focus and tracking position sensing is achieved by 2 analyzing laser light reflected from disk 30 over path 47, 3 thence through lens 45, through one-half mirror 60 and to be 4 reflected by half-mirror 61 to a so-called "quad detector"
62. The symbol 62 also includes optics, such as a hemi-6 cylinder lens, for processing a light beam before the beam 7 impinges on the detector surfaces. Quad detector 62 has 8 four photo elements which respectively supply signals on g four lines collectivQly denominated bv numeral 63 to focus and tracking circuits 54. Aligning one axis of the detector 11 62 with a track center line, track following operations are 12 enabled. Focussing operations are achieved by comparing the 13 light intensities detected by the four photo elements in the 14 quad detector 62. Focus and tracking circuits 54 analyze the signals on lines 63 to control both focus and tracking.

17 Recording or writing data onto disk 30 is next described.
18 It is assumed that magnet 48 is rotated to the desired 19 position for recording data. Microprocessor 40 supplies a control signal over line 65 to laser control 66 for indicat-21 ing that a recording operation is to ensue. This means that 22 laser 67 is energized by control 66 to emit a high-23 intensity, laser light beam for recording; in contrast, for 24 reading, laser 67 emits a reduced-intensity beam that does not heat the illuminated spot on disk 30 above the Curie 26 point. Control 66 supplies its control signal over line 68 27 to laser 67 and receives a feedback signal over line 69 28 indicating the laser 67 emitted light intensity. Control 68 29 adjusts the light intensity to the desired value. Laser 67, a semiconductor laser such as a gallium arsenide diode .

13141û0 1 laser, can be modulated by data signals so the emitted light 2 beam represents the data to be recorded by such intensity 3 modulation. In this regard, data circuits 75 (later 4 described) supply data indicating signals over line 78 to laser 67 for effecting such modulation. This modulated 6 light beam passes through polarizer 70 (linearly polarizing 7 the beam), thence through collimating lens 71 toward half 8 mirror 60 in light path 72 for being reflected toward disk 9 30 through lens 45. Data circuits 75 are prepared for recording the microprocessor 40 supplied suitable control 11 signals over line 76. Microprocessor 40 in preparing 12 circuits 75 i3 responding to commands for recording received 13 from a host processor 37 via attaching circuits 38. Once 14 data circuits 75 are prepared, data is transferred directly between host processor 3? data circuits 75 through attaching 16 circuits 38. Data circuits 75 also has ancillary circuits 17 (not shown) relating to disk 30 ancillary or format signals, 18 error detection and correction signals and the like.
19 Circuits 75, during a read or recoverv action, strip the ancillary signals from the readback signals before supplving 21 corrected data signals over bus 77 to host processor 37 via 22 attachment 38.

24 Reading or recovering data from disk 30 for transmission to a host processor requires optical and electrical processing 26 of the laser light beam from the disk 30. That portion of 27 the reflected light (which has its linear polarization fro~
28 polarizer 70 rotated bv disk 30 recording using the Kerr 29 effect) travels along the two-way light path 47, through lens 45 and half-mirrors 60 and 61 to the data detection 1 3 1 ¢ 1 ~3 1 portion 79 of the head arm 33 optics. ~alf-mirror or beam 2 splitter 80 divides the reflected beam into two equal 3 intensity beams both having the same reflected rotated 4 linear polarization. The half-mirror 80 reflected light travels through a first polarizer 81 which is set to pass 6 only that reflected light which was rotated when the remnant 7 magnetization on disk 30 spot being accessed has a "north"
8 or binary one indication. This passed light impinges on g photo cell 82 for supplying a suitable indicating signal to differential amplifier 85. When the reflected light was 11 rotated by a "south" or erased pole direction remnant 12 magnetization, then polarizer 81 passes no or verV little 13 light resulting in no active signal being supplied by 14 photocell 82. The opposite operation occurs by polarizer 83 lS which passes only "south" rotated laser light beam to photo 16 cell 84. Photocell 84 supplies its signal indicating its 17 received laser light to the second input of differential 18 amplifier 85. The amplifier 85 supplies the resulting 19 difference signal (data representing) to data circuits 75 for detection. The detected signals include not only data 21 that is recorded but also all of the so-called ancillary 22 signals as well. The term "data" as used herein is intended 23 to include any and all information-bearing signals, prefera-24 bly of the digital or discrete value type.

26 The rotational position and rotational speed of spindle 31 27 is sensed by a suitable tachometer or emitter sensor 90.
28 Sensor 90, preferably of the optical sensing type that 29 senses dark and light spots on a tachometer wheel (not shown~ of spindle 31, supplies the "tach" signals (digital 1 signals) to RPS circuit 91 which detects the rotational 2 position of spindle 31 and supplies rotational information-3 bearing signals to microprocessor 40. Microprocessor 40 4 employs such rotational signal.s for controllinq access to data storing segments on disk 30 as is widely practiced in 6 the magnetic data sto_ing disks. Additionally, the sensor 7 90 signals also travel to spindle speed control cirsuits 93 8 for controlling motor 32 to rotate spindle 31 at a constant 9 rotational speed. Control 93 may include a crystal con-trolled oscillator for controlling motor 3~ speed, as is 11 well known. Microprocessor 40 supplies control signals over 12 line 94 to control 93 in the usual manner.

14 As seen in Fig. 3, host processor 37 is operatively connect-ed to a programmable control unit 101 bv interface 102.
16 Such interface 102 can be the interface between IB~ con-17 structed host processors and the programmable control units 18 used in connection with such I~M host processors. Tn 19 addition, dash line 103 indicates special signals supplied by host processor 37 to programmable control unit 101 in 21 connection with space management of magnetooptic DASD 105.
22 Such special signals travel over the interface 102 but are 23 separately illustrated in Fig. 3 for more clearly illustrat-24 ing the invention. Such signals constitute an indication that record areas that contain recorded signals can be 26 freed, i.e., moved from the allocated status to the free but 27 not erased status. Further such indications may include 28 that the data being recorded by host processor 37 is of the 29 sequential type. Rather than recording such sequential data over previously recorded tracks, space management 37A can *Registered Trade Mark 13141~)0 1 access from SST 20 the free and erased tracks for allocation 2 to the sequential data to be next received from host proces-3 sor 37. Such allocation eliminates the need for erasing 4 previously recorded tracks before the recording occurs.
Such time saving helps the efficiencv of host processor 37.

7 In a similar manner, control unit 101 controls the operation 8 of magnetooptic DASD 105 as indicated bv the interconnection 9 106. Such controls may be the control used in connection with the apparatus described by Bohl supra. Control unit 11 101 passes the space management control as indicated by dash 12 line 107. As set forth in more detail in Fig. 4, such 13 controls are particularly directed toward VTOC 10 and the 14 surface analysis controls for initializing the disk 30 of magnetooptic DASD 105. Host processor 37 has an internal 16 memory diagrammatically represented by SST 0 which contains 17 the various fields described with respect to Fig. 1 and 18 which are used by space management 37A.

Fig. 4 illustrates in flowchart form the machine operations 21 effected in the Fig. 3-illustrated apparatus by space 22 management 37A that are pertinent to an understanding of the 23 present invention. The host processor 37 executes programs 24 for effecting the machine operations represented in Fig. 4.
One of the programs is dispatcher 110 which coordinates 26 operation of all space management program execution and has 27 a design that is well known in the programming art. Activa-28 tion of space management 37A is in accordance with known 29 programming techniques. Arrows 111 represent program calls to various programs to be executed for performing machine 1 operations not pertinent to an understanding of the present 2 invention but which are found in a control unit for a data 3 storage subsystem. As a practical matter, proqrams for 4 implementing machine operations no~ pertinent to an under-standing of the present invention would most likely be a 6 greater proportion of programs executed by host processor 7 37. Dispatcher 110 sets a priority of execution of the 8 various programs. A low level priority of the programs is 9 assigned to implement one portion of the invention when the magnetooptic DASD 105 is not recording data on disk 30 nor 11 reading data from disk 30 (i.e., not reserved or allocated).
12 Logic path 112 represents the entry into such space manage-13 ment machine operations. The first machine operation 14 indicated by numeral 113 (free NE) e~amines SST 20 field 2315 for determining whether or not there are any tracks of disk 16 30 that had been deallocated but not yet erased (free but 17 not erased -- NE). Assuming there are some free NE tracks, 18 SST 20 has a nonzero value in field 23. Space management 19 37A identifies a one of such tracks which may have a physi-cal address stored in field 23 or may require access to VTOC
21 10 third portion 16 for identifying one free NE track.
22 Control unit 101 then actuates the magnetooptic DASD 105 to 23 move fine actuator 46 to the addressed track. Then control 24 unit 101, in response to space management 37A, commands magnetooptic DASD 105 to erase that track as indicated at 26 step 114. Upon successful completion of the track erasure, 27 which uses normal data recording techniques, space manage-28 ment 37A at step 115 moves the identification of the just-29 erased track from the third VTOC portion 16 to the second VTOC portion 15 and updates SST 20 by indicating in field 22 1 that the just-erased track is now readv to receive data to 2 be recorded; the identification of any such track is deleted 3 from the free ~E field 23. At a minimum, the number of free 4 tracks but not erased indicated in numeral 23 are reduced hv one where the number of free and the number of erased tracks 6 indicated in field 22 is increased by one. Similar counts 7 are also stored in VTOC 10. Upon completion of machine 8 operations step 115, the dispatcher 110 becomes active.

Under certain circumstances, the erasure of the track in 11 step 114 may be a free-standing operation, i.e., control 12 unit 101 may be disconnected during erasure from magneto-13 optic DASn and, therefore, may return to a dispatcher 110 14 leaving an electronic note to itself to return to the machine operation 115 when the track erasure is completed.
16 While it is preferred that a single track be e-ased at a 17 time to enable a maximum number of requested recording and 18 readback operations, no limitation to a single track erasure 19 is intended.
21 In one embodiment, when space management finds no free, not-22 erased tracks at decision step 113, it then proceeds to 23 decision step 116 to determine whether or not all of the 24 record tracks of disk 30 have been formatted. It is to be understood that steps 113 and 116 may be both independently 26 activated from dispatcher 110. Space management examines 27 field 24 of SST 20 for determining whether or not a track 28 address is recorded therein. If no track address is record-29 ed or a track address having a value one greater than the address of the radially-inwardmost track of disk 30 is 131~100 1 recorded, then space management has determined that all of 2 the tracks of disk 30 have been formatted. At this point, 3 space management ollows program path 117 to return path 109 4 returning to dispatcher 110.

6 In the event that field 24 contains a physical address of a 7 new track of disk 30, then one of the new tracks is then 8 surfaced analyzed and formatted in subroutine 120. In 9 machine operations step 121, the track identified in field 24 is the next track to be formatted and is assigned for the 11 formatting operation. In step 122, space management 37A
12 causes control unit 101 and magnetooptic DASD 105 to surface 13 analyze and test the just-identified new track. Such 14 surface analysis includes detecting and identifving surface defects for later recording in the home address area of the 16 track being surfaced analyzed.

19 During the su-face analysis, either magnetooptic DASD 105 or the control unit 101 collects the identification of the 21 detected surface defects, their circumferential locations 22 and extents. Upon completion of such accumulation of 23 detected defect identifications, space manage~ent 37A moves 24 to step 123 wherein the defects are accumulated in table form ready for recording in the home address area in the 26 ensuing step 125. As a part of step 123, control unit 101 27 causes magnetooptic DASD 105 to erase the just surface-28 analvzed track. Following such erasure, the home address 29 record HA is written in that track in step 125. Step 124 ! TU987011 -22-l indicates that other da~a processing may be performed before 2 step 125 effects formatting.

4 Upon the successful completion of track formatting, field 24 of SST 20 and VTOC 10 are updated by selecting the next 6 higher track address (the address of the next radially-7 inwardmost track) for recording respectivel~ in field 24 of 8 SST 20 and in fourth VTOC portion 17. SST 20 and VTOC
g portion 15 are updated to show availability of each addi-tional formatted track. When the radially inwardmost track 11 is erased, the stored address is for no track, i.e., is one 12 greater than the highest addressed track. Upon completion 13 of machine operations step 125, program execution goes back 14 to dispatcher 110.

16 Dispatcher 110 also activates allocate-deallocate module 17 128. Allocate-deallocate module 128 may also be called by 18 another program module being eYecuted for performin~ an 19 allocate request generated in host processor 37. In ans~
event, allocate-deallocate module 128 is constructed and 21 performs operations as found in present day memory control 22 computers which allocate and deallocate addressable data 23 storage areas. If allocate module 128 during an allocation 24 procedure being performed finds an unallocated erased addressable track identified either in SST 20 field 22 or in 26 second VTOC portion 15, the allocation is successful. Such 27 successful allocation results in indicating the allocation 28 is complete over line 129 for enabling the host processor to 29 command recording in the just allocated data storage area.
Tf the allocate procedure was caused by execution of another .. . . . . .

1 program within host processor 37 sending a requ~st over line 2 127A, then the successful allocation is indicated on line 3 129A to enable that program execution to be continued.

All deallocations of tracks by module 128 are successful.
6 Each deallocation includes moving the identification of the 7 record track or tracks being deallocated from the first VTOC
8 portion 14 as an allocated track to third VTOC portion 16 9 and SST 20 which indicates the track is unallocated but not erased. Space management may not know whether or not data 11 in fact had been recorded in the just deallocated track, 12 however, for purposes of integrity, it is assumed that some 13 data has been recorded in the just dealloca~ed track. All 14 of the above-described operations are represented in Fig. 4 by numeral 131. Execution of these operations completes the 16 deallocation procedure for enabling dispatcher 110 to select 17 another program for execution.

19 When an allocation attempt fails hecause there are no addressable data storage tracks identified in the second 21 VTOC portion 15, the numbers of free and erased tracks 22 indicated in field 22 of SST 20 and second VTOC portion 15 23 are zero, then space management has to be performed at the 24 next available moment for obtaining additional allocatable data storage space.

27 The failed allocate program path 132 leads to decision step 28 133 to determine whether or not there are any free NE record 29 tracks identified in third VTOC portion 16 as also indicated hy a nonzero number in field 23 of SST 20. When SST field .. ... . . . . .

1 23 is nonæero, then execution of the machine operations of 2 Fig. 4 proceeds to erase tracks in step 134 for making those 3 tracks available for allocation. Upon the completion of 4 erasure, the number in field 23 is reduced while the number in field 22 is made nonzero; VTOC 10 is updated to reflect 6 the erasure by moving the indication of the just erased 7 tracks from third VTOC portion 16 to second VTOC portion 15.
8 Following the successful completion of erasure, the just-g erased tracks then are allocated in step 135 wi.h space management then returning to dispatcher 110.

12 In the event there are no unallocated NE tracks detected at 13 decision step 133, then some remaining unformatted tracks on 14 disk 30 are processed. At decision step 138 (all FMT), space management examines SST 20 field 24 for determining 16 whether or not there are anv remaining unformatted tracks on 17 disk 30. If there are none, all of the tracks on disk 30 18 have been formatted, then space management follows path 139 19 to dispatcher 110, i.e., there is nothing that can be done to satisfy the allocation request at this time -- the disk 21 is fully allocated. On the other hand, at decision step 22 138, if there are some unformatted tracks indicated by Cield 23 24 of SST 20 or fourth VTOC portion 17, then at least one of 24 the unformatted tracks, and if more than one track has been requested, a plurality of such unformatted tracks are 26 formatted at function step 140. Function step 140 includes 27 all of the steps set forth with respect to formatting in the 28 subroutine 120. It is to be noted that surface 29 analysis of the tracks may be completed yet the TU987011 -~5-1 formatting of the analyzed tracks (step 125) may not have 2 yet been completed. In this later instance, only step 125 3 of subroutine 120 is performed.

Upon completion of formatting a requisite number of unfor-6 matted tracks at step 140, space management proceeds to 7 allocate the just foxmatted and erased tracks at step 135.
In a practical implementation, the programming used for 9 performing operation step 135 is a part of allocate module 128.

12 All of the above description relates to erasing and format-13 ting tracks on an in-line basis in which host processor 37 14 interleaves such erasing operations and formatting opera-tions between recording and readback operations. To ini-16 tialize disk 30 when first placed on magnetooptic DASD 105 17 or when disk 30 is a non-removable disk when magnetooptic 18 DASD 105 is first varied on to host processor 37, space 19 management initializes a radial-outwardmost set of record tracks for enabling recording and readback operations to 21 ensue. In an alternative procedure, a factory may perform 22 the initial formatting of the radially-outward tracks in 23 disk 30. In that event, space management 24 does not initialize the disk 30 in a user ~5 environment. Initialization may also be 26 instituted by space management causing 27 control unit 101 to sense the disk 30 for VTOC 10; if there 28 is no VTOC 10 indicates an unformatted disk. Then initial-29 ization can be started by space management. In any event, an initialization command is sensed at decision step 154.

1 If the initialization command had previously been performed 2 for disk 30, as can be sensed by reading VTOC 10, then no 3 action is taken. For an uninitialized disk 30, space 4 management proceeds from decision step 154 to a series of steps 155-157. At step 156, a surface test 6 or analysis is made of a predetermined 7 number of radially-outwardmost tracks 8 on disk 30. For 9 example, the first 100 radially-outwardmost tracks are surface analyzed as described with respect to the steps 120.
11 Upon completion of the surface analysis, the tracks are 12 erased and home addresses (HAs) are written on the respec-13 tive tracks during step 155 including the outermost track 14 which is to receive VTOC 10. Then, at step 157, the VTOC 10 is written in the outermost track. Upon completion of this 16 disk initialization, space management returns to dispatcher 17 110 for enabling host processor 37 to perform other machine 18 operations via return path.

Fig. 5 illustrates machine operations used when non-21 sequential data is being recorded, i.e., those situations 22 wherein host processor 37 desires to maintain the data in 23 the same track that a previous version of the data was 24 stored. It is to be understood that host processor 37 can be programmed to allow movement o non-sequential data from 26 track to track on disk 30 for avoiding interleaving an 27 erasure step between a request to write and the actual 28 writing or recording operation on disk 30. In the latter 29 instance, the director~ of the data stored on disk 30 is loqical, i.e., VTOC 10 includes a director~ which converts a . ~ . . , ., .. . . . ~ .. .

1314~oo 1 logical number or address into a physical or track address.
2 Such logical addressing is found in present day diskettes 3 and hard disks as used with personal computers. In any 4 event, assuming all o the above is not desired, then at path 164 a host processor 37 issued write command is to be 6 executed by control unit 101. At decision step 165, space 7 management determines whether or not it is an update write 8 operation. If it is an update operation, i.e., new data is 9 to replace currently stored data, then at function step 166, control unit 101 is commanded to erase the target area. A
11 channel command retry signal is sent to host processor 37 by 12 control unit 101 upon completion of step 16S. Upon comple-13 tion of the erasure at step 166, a DE~ICE END signal is sent 14 by control unit 101 to host processor 37 signalling comple-tion of the erAsure. Then the data is written to disk 30 at 16 function step 177. Upon completion of function step 177, 17 host processor 37 returns to other program steps (not sho~7n) 18 not pertinent to an understanding of the present invention.

If on the other hand at decision step 165 space management 21 determines that the data is original data and the write is 22 not an update, then at decision step 170 space management 23 determines whether or not there are any free and erased 24 tracks ready for allocation. I- not, then a track is erased as described with respect to Fig. 4 and is represented in 26 Fig. 5 by step 169. When a free and erased track (F-E) is 27 found bv decision step 170 or upon completion of the erasure 28 step 169, space management at step 171 allocates the track 29 to the write operation. Then the write operation is actual-ly performed at function step 177.

., . .. i . . .. ,,.. . ~.

1 3 1 4 ~ 00 1 While the invention has been particularly shown and de-2 scribed with reference to preferred embodiments thereof, it 3 will be understood by those skilled in the art that various 4 changes in form and details may be made therein without departing from the spirit and scope of the invention. In 6 particular, the invention may be applied to hard sectored 7 media, fixed block architecture media, updatable media and 8 the like.

Claims (20)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a record medium for storing data, the medium having a large multiplicity of addressable rewritable data storage areas:
the improvement including, in combination:
a volume table of contents (VTOC) recorded on the medium for indicating the data contents of the medium;
first indicia in VTOC for indicating allocated ones of the addressable data storage areas;
second indicia in VTOC for indicating unallocated ones of the addressable data storage areas that are still storing data;
third indicia in VTOC for indicating unallocated ones of the addressable data storage areas that are erased as to not be storing any data; and fourth indicia in VTOC indicating unformatted ones of the addressable data storage areas that cannot receive data for storage until predetermined format signals are recorded therein.

2. In the record medium set forth in claim 1, further including, in combination:
said second indicia being sorted by addresses of the respective data storage areas; and said fourth indicia constituting a single address of a one of the unformatted addressable data storage areas that is addressable by a lowest address of all the addresses of the unformatted data storage areas.

3. In the record medium set forth in claim 1, further including, in combination:
said record medium being a rotatable disk with a multiplicity of substantially circularly concentric tracks, each of said addressable data storage areas including a one of said tracks;
one of said addressable data storage areas including a radially outwardmost one of said addressable data storage areas; and all of said first, second, third and fourth indicia being in said one addressable data storage area.

4. In the record medium set forth in claim 1, further including, in combination:
said record medium being a record disk having a plural-ity of concentric record tracks with each of the record tracks having a single index indicia, each of said record tracks including a one of said addressable data storage areas; and each of said tracks that is represented by either of said first, second or third indicia having a home address record in immediate juxtaposition to the respective index mark which home address record containing rotational loca-tions of defects in the respective record tracks and all of the tracks represented by said fourth indicia not having said home address record.

5. In the record medium set forth in claim 4, wherein the record medium has optically writeable and sensible data storage areas.

6. In a method of managing data storage space on a record disk;
the steps of:
receiving a record disk having a multiplicity of concentric record tracks, each track having a sensible index mark and indications of the circular extent of the track;
initializing the record disk for data recording by the steps of:
a) surface analyzing a radially outward set of a predetermined number of said tracks, said predetermined number being substantially less than the total number of tracks on the record disk, indicating the location and extent of each detected surface defect b) recording in each of the surface analyzed tracks, indications of the rotational positions of surface defects in the respective surface analyzed track; and c) recording a volume table of contents in a radially outermost one of the said record tracks in said outward set to contain the address of the tracks in the outward set as being free tracks available to be allocated for data storage and an indication that all of said tracks other than said outward set are not available for data storage until format-ted.

7. In the method set forth in claim 6, further including the steps of:
placing the disk in an information handling environ-ment, including allocating ones of the free tracks for data storage, recording signals into and reading signals from ones of said allocated tracks;

recording in said volume table of contents which of said formatted tracks are currently allocated for storage of data;
when the disk is not being used for receiving signals to be recorded or for supplying recorded signals, formatting additional ones of said unformatted tracks beginning at a radial outermost one of the remaining unformatted tracks;
and updating said volume table of contents to indicate a current radially outermost one of the remaining unformatted tracks and the additional ones of the tracks are available for data storage.

8. In the method set forth in claim 7, further including the steps of:
deallocating ones of the allocated tracks which may contain data stored therein;
when the disk is not being used for receiving signals to be recorded on the disk or for supplying recorded signals from the disk erasing said free but not erased tracks; and recording in said volume table of contents which of the free tracks have been erased and which of the free tracks contain not erased data.

9. In the method set forth in claim 8, further including the steps of:
delaying formatting additional ones of said unformatted tracks until all of the free but not erased tracks have been erased.

10. In the method set forth in claim 9, wherein said erasing and formatting steps performed when the disk is not being used being limited to one track per operation; and performing data recording and data readback operations and repeating said one track operation intermediate time spaced ones of said recording and readback operations.

11. In the method set forth in claim 10, wherein said record disk has a magnetooptic recording area which requires erasure before recording, further including the steps of:
updating a record in the magnetooptic recording area which is substantially less than the extent of a record track, delaying recording while erasing the portion to be updated, then recording the updated portion on the erased portion of the record track.

12. In the method set forth in claim 11, further including the steps of:
receiving an indication that signs are to be recorded which are updates of currently recorded signals;
identifying those portions to receive the updated signals and erasing those portions; and then receiving the updated signal and recording same in the erased portions.

13. In the method set forth in claim 10, further including:
receiving an updated set of data signals for data already recorded on the disk;
allocating a freed and erased unallocated track for receiving the updated data;
recording the updated data onto the just allocated track; and erasing the data from the original track.

14. In a data storage subsystem having a control unit including program means for operating the control unit and the subsystem, a disk recorder operatively coupled to the control unit and having a large capacity disk recording surface;
the improvement including, in combination:
operating program means including a program dispatcher in said control unit for effecting subsystem operation which includes recording data onto the large capacity disk surface and reading data recorded on the disk surface;
formatting program means in the control unit, including surface analysis controlling program means and home address recording program muons which records locations of defects in a respective track in a home address record in such track;
said dispatcher having initialization programming means operative to cause the control unit to check the large capacity disk surface to determine whether or not the disk surface has been initialized, and if not initialized, operative to activate the formatting program means a given plurality of times for surface analyzing and formatting a predetermined number of record tracks at a radial outward portion thereof and recording a volume table of contents (VTOC) in a radial outward most one of said predetermined set of tracks;
the dispatcher having further intermediate format initiating program means activated when the large capacity disk surface is not currently primed for recording or supplying readback signals from and to the control unit for activating said formatting program means to format a second predetermined number of said unformatted record tracks, beginning with a radially outwardmost one of the unformatted record tracks; and said dispatcher cycling through all of its operations such that said intermediate formatted program means is activated as a lower priority one of operations to be performed in the subsystem.

15. In the subsystem set forth in claim 14, wherein said intermediate formatting means selects a single record track to be surface analyzed and formatted by said formatting program means.

16. In the subsystem set forth in claim 14, further includ-ing, in combination:
erasure program means in the control unit actuatable by said dispatcher program means whenever said large capacity disk surface is not primed for recording data signals or supplying readback data signals for erasing data tracks on the large capacity disk surface which are not indicated as being used for data recording;
allocation program means in the control unit for allocating ones of said record tracks for receiving data signals and indicating to the allocated ones of the record track as being used for data recording and including means for recording the status of the tracks in said VTOC; and said dispatcher giving the erasure program means priority over said intermediate formatting program means.

17. In the subsystem set forth in claim 16, wherein said large-capacity disk surface has an active recording layer which requires erasure before any recording.

18. In the subsystem set forth in claim 16, further includ-ing, in combination:
program means in the control unit actuatable by said dispatcher to allocate a free and erased track to receive updated data for recording and maintaining the same address-ability for the updated data as is established for the originally recorded data.

ing, in combination:
said reallocating program means actuating said erasure programming means for erasing the old data track after the newly allocated record track has received the updated data.

TU987011

20. In a record medium of the rotatable disk type for storing data, the medium having a large multiplicity of addressable data storage tracks which are concentrically arranged on the rotatable medium;
the improvement including, in combination:
a volume table of contents (VTOC) recorded on the medium in a radially outward one of said record tracks for indicating the data content and the current status of the record tracks on the medium;
first indicating data stored in said VTOC for indicat-ing allocated ones of the addressable data storage tracks;
second indicating data stored in said VTOC for indicat-ing unallocated ones of the addressable data storing tracks;
and fourth indicating data stored in said VTOC for indicat-ing unformatted ones of the addressable data storing tracks that cannot receive data for storage until predetermined format signals are recorded therein.