GB2410605A - Write once read many tape drive - Google Patents
Write once read many tape drive Download PDFInfo
- Publication number
- GB2410605A GB2410605A GB0402031A GB0402031A GB2410605A GB 2410605 A GB2410605 A GB 2410605A GB 0402031 A GB0402031 A GB 0402031A GB 0402031 A GB0402031 A GB 0402031A GB 2410605 A GB2410605 A GB 2410605A
- Authority
- GB
- United Kingdom
- Prior art keywords
- data
- tape
- recorded
- worm
- cartridge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000013500 data storage Methods 0.000 claims description 23
- 238000000034 method Methods 0.000 claims description 17
- 239000004065 semiconductor Substances 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 238000004891 communication Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000013144 data compression Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
- G11B23/28—Indicating or preventing prior or unauthorised use, e.g. cassettes with sealing or locking means, write-protect devices for discs
- G11B23/288—Protecting disks from being written or overwritten
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/12—Formatting, e.g. arrangement of data block or words on the record carriers
- G11B20/1201—Formatting, e.g. arrangement of data block or words on the record carriers on tapes
- G11B20/1202—Formatting, e.g. arrangement of data block or words on the record carriers on tapes with longitudinal tracks only
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/11—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information not detectable on the record carrier
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
- G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
- G11B27/30—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording
- G11B27/3027—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording used signal is digitally coded
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B2020/10898—Overwriting or replacing recorded data
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/20—Disc-shaped record carriers
- G11B2220/21—Disc-shaped record carriers characterised in that the disc is of read-only, rewritable, or recordable type
- G11B2220/215—Recordable discs
- G11B2220/218—Write-once discs
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/60—Solid state media
- G11B2220/65—Solid state media wherein solid state memory is used for storing indexing information or metadata
- G11B2220/652—Solid state media wherein solid state memory is used for storing indexing information or metadata said memory being attached to the recording medium
- G11B2220/655—Memory in cassette [MIC]
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/90—Tape-like record carriers
Abstract
A tape storage system 10 allows data to be written at the end of previously written data but does not allow data to be overwritten. The system keeps track of the number of records and file marks written in order to know where to append data. The information may be stored in a semiconductor memory 18 in the tape cartridge 17. The system may be able to overwrite file marks written at the end of the data.
Description
24 1 0605
DATA STORAGE METHOD AND APPARATUS EMPLOYING A TAPE CARTRIDGE
FIELD OF THE INVENTION
This invention concerns methods and apparatus for storing data, and more specifically to data storage methods and apparatus which employ a tape cartridge.
BACKGROUND OF THE INVENTION
Tape cartridges in use today incorporate a magnetic tape having data tracks for recording a succession of units of information known as data sets. Each data set consists of a data region within which data is recorded and a data set information table that describes the content of the data region. Data to be recorded is sent to the cartridge by a tape drive and is recorded within the data regions. The data set information table for each data set has a multiplicity of fields each of which has a pre-allocated number of bytes of storage. The fields store records of information such as the data set number, the valid data length, the data set type, and the drive manufacturer identity.
Data written to the tape may be protected from being overwritten. Such data is protected by drive level processing that renders the tape as write-once-read many (WORM) protected. When trying to protect data written to tape in a WORM environment, safeguards are implemented to prevent the data from being overwritten, accidentally or intentionally.
The use of WORM media usually implies that data, once written to tape, cannot be overwritten. However some applications require that a recording session should end with the recording of two file marks preceding a data set denoting the end of data. Then, when performing a subsequent recording session, the application will position between the two file marks and start recording the new data. This requires that the second of the two file marks should be overwritten.
If no file marks have been recorded at the end of a recording session due, for example, to the loss of power to the tape drive while the recording session is in progress, the tape would no longer be useable for performing further recording sessions. Furthermore, the last recording session might not be complete and the recording session would have to be repeated on a different tape.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a method of recording data in data storage apparatus comprising a tape cartridge having a data storage tape, the method comprising the steps of; recording WORM data in a succession of data sets along the data storage tape, the data sets including data records and file marks, calculating a count of the data records and file marks to determine the logical position of the end of WORM data, and recording further WORM data from a starting position indicated by the said count.
The recording of the further WORM data will overwrite any file marks previously recorded beyond the end of WORM position indicated by the said count.
Further according to the present invention, there is provided a data storage apparatus comprising a tape drive adapted to receive a tape cartridge having a data storage tape, the apparatus being programmed to record WORM data in a succession of data sets along the data storage tape, the data sets including data records and file marks, the data storage apparatus being further programmed to calculate a count of the data records and file marks to determine the logical position of the end of WORM data and to record further WORM data from a starting position indicated by the said count.
DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference to the accompanying drawings in which; Figure 1 is a block diagram of the hardware components and interconnections of a data storage system according to the present invention, Figures 2 and 3 show a tape cartridge included in the system of Figure 1, Figure 4 is a block diagram of transponders and memory included in the data storage system of Figure 1, Figures 5, 6, 7 and 8 are diagrams of data recording on a tape included in the tape cartridge of Figures 2 and 3, and Figure 9 is a flow diagram illustrating steps in a method embodying the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to Figure 1, there is shown a data storage apparatus 10 embodying the present invention coupled to at least one hierarchically superior host 11. The data storage apparatus includes a controller 12 connected to the host 11 by an interface 13. The data storage apparatus also includes a tape drive 14, including a drive engine 15 and drive mechanism 16, that receives a tape cartridge 17 that has a cartridge memory 18. A controlling software application on the host 11 controls the tape drive 14 to read data from and write data to the tape storage cartridge 15.
The host system 11 has at least one central processing unit l5 (CPU) and a memory to store the controlling software application. The interface 13 connecting the host system 11 to the data storage apparatus 10 is preferably a Small Computer Systems Interface (SCSI) or a USB (Universal Serial Bus). The method of communication over either of these standard busses is known to those skilled in the art.
The drive mechanism 16 includes electrical and mechanical components that receive, position and access tape cartridges. The drive mechanism has components to lock a tape cartridge in place, an ejection motor and read/write heads. The drive engine 15 is a data processor that is programmed to supervise the operation of the drive mechanism 16 and to manage the flow of data to be recorded in or read from a tape cartridge 17 received in the drive 14.
Figures 2 and 3, show a general view of the cartridge 17 including a structural casing 19 within which are located the cartridge memory 18 and a magnetically recordable tape.
The cartridge is an implementation of Linear Tape Open (LTO) technology. The tape is supported on a rotatable tape reel or spool and has a leader by means of which the tape drive 14 can uncoil and withdraw the tape from the cartridge reel or spool for data reading or recording.
Referring to Figure 4, the cartridge memory 18 includes a transponder 21 and a memory area 18a that has the capability l0 of non-volatile storage and is preferably an EEPROM (electronically erasable programmable read only device).
The transponder 21 consists of a transmitter 22, a receiver 23, an aerial 24 and a processor 25. The cartridge memory 18 co-operates with a transmitter/receiver module 26 Is incorporated into the tape drive 14. The module 26 includes a serial interface 27 to the tape drive, a processor 28, a transmitter 29, a receiver 30 and an aerial 31. The transponder 21 incorporated into the cartridge 17 is inductively powered by the transmitter/receiver module 26 and data is exchanged between the transmitter/receiver 22,23 of the transponder 21 and the transmitter/receiver 29,30 of the module 26 by way of the inductively coupled aerials 24 and 31. The aerials 24 and 31 thus provide a contactless coupling of the cartridge memory 18 to the tape drive 14 for 2s data transfer between the cartridge memory and the tape drive when the tape cartridge 17 has been received by the tape drive. In the case where the cartridge is to be WORM protected, the information provided by the cartridge memory indicates that the cartridge is WORM protected and that WORM protected data written to the tape is not to be overwritten.
The cartridge memory area 18a stores information including usage information, cartridge manufacturer information and cartridge memory manufacturer information. The cartridge manufacturer information includes the cartridge type, a serial number of the cartridge and an identification of the manufacturer. The cartridge memory manufacturer information S includes the serial number of the transponder, the type of transponder and the serial number of the cartridge memory.
Figures 5 and 6 are diagrammatic representations of the manner in which data is recorded on the tape. Each of lO Figures 5 and 6 show a short portion only of the tape. There are five servo bands 32 pre-recorded on the tape that are used for track following while the cartridge is being operated in the cartridge drive 14. The servo bands are written before the cartridge is usable for data storage and lS are located at predefined specific distances from one edge of the tape that is referred to as the tape reference edge.
Each servo band contains servo frames encoded as longitudinal position words to provide an indication of the position down the length of the tape. In a preferred embodiment of the invention, the longitudinal position words each comprise 36 servo frames which increment in value as the tape is removed from the cartridge in the forward direction within a range from O to 7 529 535.
Each of the four areas between adjacent pairs of servo bands is a data band 33, the bands being numbered 2, 0, 1 and 3 respectively with data band 2 being nearest to the tape reference edge and data band 3 being furthest from the tape reference edge. The four data bands each have 128 data tracks arranged in eight data sub bands as shown in Figure 6. The 16 data tracks in a sub band are accessed in a spiral manner in forward and reverse wraps. Forward wraps are recorded while the tape is moving from the beginning of the tape to the end of the tape and reverse wraps are recorded while the tape is moving from the end of the tape to the beginning of the tape.
Figure 7 shows the way in which data is transformed as it flows from the host 11 to the recorded tape. The data conforms to a data format in which data is logically divided into records 34 and file marks. Each record 34 is processed l0 by the host to compute a cyclic redundancy check (CRC) character 35 that is added to the record to form a protected record 36. The CRC character is useful in the detection of errors. A data compression algorithm processes the protected records 36 and file marks to produce a stream of symbols 37 broken into sets of host data 38 to which a data set information table (DSIT) 39 is added. The host data and data set information table (DSIT) 39 together constitute a data set 40.
Figure 8 shows the tape laid out in diagrammatic form from the beginning of the tape labelled BOT to the end of the tape labelled EOT. Data sets are recorded along the tape beginning with a format identification data set FID, followed by user data sets and ending with an end of data set labelled EOD. A blank unrecorded portion of the tape extends from the end of data set EOD to the end of the tape EOT. Two controlling file marks 41 and 42 are recorded in the portion of tape between the last user record and the end of data (EOD). The file marks are recorded at the end of the recording session under the control of the controlling software application. The data recorded from the beginning of the tape up to the first of the controlling file marks 41 is WORM data. In the event that further user data is to be appended to that already recorded on the tape, the controlling application will position between the two controlling file marks 41 and 42 and start writing the new data. This process requires that the second of the two file marks 42 is overwritten.
If a recording session is not properly completed because, for example, the tape drive suffers a power failure l0 or the controlling software application is inadvertently interrupted, the controlling file marks may not be recorded.
Under these circumstances, the recorded WORM data will be incomplete and it will not be possible to append further data using an application reliant on the controlling file l5 marks. The tape may thus be rendered unusable and it may be necessary to repeat the recording session using a different tape cartridge.
To overcome these difficulties, when writing to tape, the tape drive calculates a logical count as the sum of records and file marks received from the host 11 from the start of the tape up to the current position. When each data set is filled, the drive puts the current count of records and file marks into the DSIT for the data set so that it is possible to identify a specific logical position from the DSIT's. The count is registered in the cartridge memory 18 to indicate the logical position at the end of every wrap on the tape. When appending further data to the tape, the tape drive resumes the count from the logical position of the append point.
When the tape drive receives a command taking it out of writing mode an end of WORM location is calculated. This location could alternatively be calculated when the tape cartridge is unloaded. The end of WORM location identifies the logical position at the end of all user data except file marks just before the end of data EOD. This allows a subsequent backup to overwrite any file marks that are located immediately before the end of data EOD.
Figure 9 illustrates the routine for writing data to the tape. In a first step 43, the current logical position is determined. In step 44 the end of WORM location is extracted from the cartridge memory 18 and compared in step to check if the end of WORM location is greater than the current logical position. If the result of the comparison is positive, writing of data is permitted in step 46. If the result of the comparison is negative, writing is prevented and an error is reported in step 47.
What has been described is a method to record data and to overwrite data during a session as long as the data is located beyond the end of WORM location. It is also possible to recover a tape that has been left in a bad state by a power failure so as to perform an interrupted backup again from the same location. Such a tape no longer has to be regarded as unusable for backup and is not forced to be totally write protected.
Claims (11)
1. A method of recording data in data storage apparatus comprising a tape cartridge having a data storage tape, the method comprising the steps of; recording WORM data in a succession of data sets along the data storage tape, the data sets including data records and file marks, calculating a count of the data records and file marks to determine the logical position of the end of WORM data, and recording further WORM data from a starting position indicated by the said count.
IS
2. A method as claimed in claim 1 in which the data is stored as a succession of data sets recorded in data tracks accessed in a spiral manner in forward and reverse wraps, the forward wraps being recorded while moving the tape from the beginning of the tape to the end of the tape and the reverse wraps being recorded while moving the tape from the end of the tape to the beginning of the tape.
3. A method as claimed in claim 2, in which the tape cartridge has a cartridge memory and the count is stored in the cartridge memory at the end of every wrap.
4. A method as claimed in claim 1, 2 or 3, in which the data is stored in data sets each of which has a data set information table and the count is stored in the data set information table of each data set.
5. A method as claimed in any one of the preceding claims, wherein the step of recording further WORM data includes the step of overwriting a file mark recorded on the tape.
6. A method as claimed in claim 5, in which the tape includes a data set signifying an end of data and the step of overwriting a file mark recorded on the tape comprises overwriting a file mark recorded between the end of WORM position and the end of data.
7. A data storage apparatus comprising a tape drive adapted to receive a tape cartridge having a data storage tape, the apparatus being programmed to record WORM data in a succession of data sets along the data storage tape, the data sets including data records and file marks, the data storage apparatus being further programmed to calculate a count of the data records and file marks to determine the logical position of the end of WORM data and to record further WORM data from a starting position indicated by the said count.
8. Apparatus as claimed in claim 7, in which the data sets are recorded in data tracks accessible in a spiral manner in forward and reverse wraps, the forward wraps having been recorded while moving the tape from the beginning of the tape to the end of the tape and the reverse wraps having been recorded while moving the tape from the end of the tape to the beginning of the tape.
9. Apparatus as claimed in claim 8, in which the apparatus is programmed to store the count in a cartridge memory of the tape cartridge at the end of every wrap.
10. Apparatus as claimed in claim 7, 8 or 9, in which the data is stored in data sets each of which has a data set information table and the count is stored in the data set information table of each data set.
11. Apparatus as claimed in any one of claims 7 to 9, programmed to overwrite a file mark recorded on the tape when recording the said further WORM data.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0402031A GB2410605A (en) | 2004-01-30 | 2004-01-30 | Write once read many tape drive |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0402031A GB2410605A (en) | 2004-01-30 | 2004-01-30 | Write once read many tape drive |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0402031D0 GB0402031D0 (en) | 2004-03-03 |
| GB2410605A true GB2410605A (en) | 2005-08-03 |
Family
ID=31971726
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0402031A Withdrawn GB2410605A (en) | 2004-01-30 | 2004-01-30 | Write once read many tape drive |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2410605A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008052794A1 (en) * | 2006-11-02 | 2008-05-08 | Fast Lta Ag | Write protection method and device for at least one random access memory device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319503A (en) * | 1990-01-26 | 1994-06-07 | Teac Corporation | Method and apparatus for writing successive streams of data on a magnetic medium by writing a cancel mark indicating the cancellation of a previously-written file mark |
| EP1302942A2 (en) * | 2001-10-09 | 2003-04-16 | Hewlett-Packard Company | WORM magnetic tape system |
| US6674596B1 (en) * | 1999-03-17 | 2004-01-06 | Sony Corporation | Memory in cassette has use restriction recorded in read-only memory |
-
2004
- 2004-01-30 GB GB0402031A patent/GB2410605A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319503A (en) * | 1990-01-26 | 1994-06-07 | Teac Corporation | Method and apparatus for writing successive streams of data on a magnetic medium by writing a cancel mark indicating the cancellation of a previously-written file mark |
| US6674596B1 (en) * | 1999-03-17 | 2004-01-06 | Sony Corporation | Memory in cassette has use restriction recorded in read-only memory |
| EP1302942A2 (en) * | 2001-10-09 | 2003-04-16 | Hewlett-Packard Company | WORM magnetic tape system |
Non-Patent Citations (1)
| Title |
|---|
| ECMA-319 Data Interchange on 12,7 mm 384-Track Magnetic Tape Cartridges - Ultrium-1 Format * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2008052794A1 (en) * | 2006-11-02 | 2008-05-08 | Fast Lta Ag | Write protection method and device for at least one random access memory device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0402031D0 (en) | 2004-03-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |