JPH02307116A - Storage subsystem - Google Patents

Abstract

PURPOSE:To omit the selection of devices required for each file in response to the due characteristic and to attain the unitary control in a storage subsystem by setting a sequence mode and an address designation mode within each storage medium and controlling the action of each deck based on the mode setting information. CONSTITUTION:A storage subsystem 1 consists of a deck group 12 including plural decks 121 - 12N to which a replaceable storage medium is mounted, a storage subsystem control part 11, and a panel switch 13. The part 11 includes a mode setting/deciding part 110 and a mode setting table 111. Then an access mode is set in the same subsystem 1 with use of a storage medium of the same type. As a result, a sequential storage form attaching importance to the store bit cost is freely mixed with an address designation type storage form attaching importance to the random access performance. Thus it is possible to satisfy the various file request conditions in the system 1 and to attain the unitary control of these conditions.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an external storage device in an information processing system, and the present invention relates to an external storage device in an information processing system, and the present invention relates to an external storage device in an information processing system. There are two modes: sequential reading and writing of data with write access (hereinafter referred to as sequential mode), and mode in which an arbitrary address is specified and read/write access is made directly to the information storage area at that address (hereinafter referred to as address specification mode). (called mode)
A removable storage medium (
For example, the present invention relates to a storage subsystem using a rewritable optical disk (for example, a rewritable optical disk, etc.).

[Prior art]

In general, in information processing systems, depending on the characteristics of the file to be created, there are files for which it is advantageous to use a direct access method that allows for high-speed random access, and for files that are mainly sequential access and data storage capacity by using a data compression function. There are some files that can be expected to have a significant reduction. Currently, the former uses magnetic disk devices and current optical disk devices, and the latter uses magnetic tape devices. In the future, especially when storing image-related information, the amount of data per code will rapidly increase, and emphasis will be placed on increasing the speed of devices equipped with compression mechanisms. There is also a strong demand for economicalization of random access files, including the former.

First, we will explain the characteristics of each current device.
A typical conventional storage device using a removable medium is a magnetic tape device. A magnetic tape device is based on the premise that access is always performed sequentially starting from the first information, and information regarding addresses is stored in tape marks, BOT (start of tape), and EO.
T (end of tape) and tape mark (file delimiter) are used to normally access the storage area immediately after being read or written in the previous access.

In other words, when reading and writing, the software does not issue positioning commands for specifying addresses. With this method, there is no need to be aware of the size of the data written immediately before, and the software continues to write sequentially until there is no more memory capacity available for writing. access. This is true even when the data length is not clear in advance for files that are accessed sequentially, or when the data length can only be determined at the time of writing due to the data compression function in the storage subsystem.

It has the advantage of being easy to control and making effective use of equipment capacity.

In fact, this type of storage subsystem, which also has a compression mechanism, has already been developed and the bit price is low, making it ideal for storing large-capacity files. However, since there is no awareness of addresses, there are disadvantages such as having to read sequentially to the target block when trying to perform random access.

On the other hand, for the data tracks of magnetic disk devices and rewritable optical disk devices that can be accessed sequentially or directly, cylinder addresses are assigned in units of concentric circles, and head addresses are assigned depending on the position of the read head. By combining information, it is possible to directly access the target data, or to format a fixed length data block, set a block address from the beginning of the data block, and use that address as a key to directly access the target data. method is adopted.

All of these methods are formatted in advance so that data of a specific data length is stored, and by specifying the address before accessing the data, it is possible to directly access the data at that address. , which improves performance during random access at the expense of some effective use of media capacity.

[Problem to be solved by the invention]

As described above, currently, magnetic tape devices (including rewritable optical disk devices) are treated as completely different devices, and current storage subsystems cannot satisfy the various file requirements of the system. There was a problem in that it was not possible to provide a storage subsystem that could centrally manage the data. On the other hand, 1.For example, rewritable optical disks have a medium capacity of over 300MB on one side, which exceeds the current magnetic tape device, and the bit cost is low.As such, it is necessary to reduce the bit cost. There is a need for a storage subsystem that satisfies the characteristics of usage as a magnetic tape device and as a magnetic disk device emphasizing random access.

The present invention has been made to solve the above problems.

An object of the present invention is to provide a storage subsystem using a removable storage medium (for example, a rewritable optical disk) that can switch between an access mode like a magnetic disk device and a mode like a magnetic tape device. An object of the present invention is to provide a storage subsystem that can be selected at the time of mounting on a read/write device (hereinafter referred to as a deck) for an exchange medium.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a removable disk storage medium that performs sequential reading and writing of data and reading and writing of data by arbitrary addressing, and a plurality of disk storage media that mount the storage medium. a reading/writing device;
In a storage subsystem equipped with a control device that controls them, there are two modes: a first mode in which read/write access is made to a storage area at an arbitrary address; Set one of the second modes for read/write access to the information storage area position in the removable medium, and if the first mode is specified, specify the access position. Based on instructions from the host device, a storage area for reading and writing is selected, and if the second mode is specified, when the storage medium is mounted, it is positioned at the first writable storage area. , is characterized in that each time a read or write instruction for the same medium is received, it is positioned in the next storage area.

[Function J] According to the above-mentioned means, within the same storage subsystem,
By using the same type of storage media and setting the access mode, there are two modes: direct access by specifying the access address like a magnetic disk drive, and a mode where the first data is accessed without specifying an address like a magnetic tape drive. A mode in which data is read/written sequentially from the storage area can be freely mixed.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be specifically described using the drawings.

In addition, in all the figures for explaining an example.

Components having the same function are given the same reference numerals, and repeated explanations thereof will be omitted.

FIG. 1 is a block diagram showing the overall schematic configuration of a storage subsystem according to an embodiment of the present invention.

In the figure, a storage subsystem 1 includes multiple decks on which removable storage media are mounted! The storage subsystem control section 11 includes a deck group 12 consisting of 21 to 12N, a storage subsystem control section 11, and a panel switch 13.
It consists of

FIG. 2 is a detailed configuration diagram of the main parts of the system of FIG. 1, and shows an example in which the information storage area of the replaceable storage medium 2 is divided into a user storage area 20 and a control information setting area 21. .

The mode setting table 111 includes information for each deck (121 to 12
Corresponding to N), an area for storing an unused/existing valid data indicating bit 112, a sequential mode/addressing mode indicating bit 113, and the block address most recently accessed when the sequential mode is set. 114
It consists of

In addition, 4 indicates the configuration of commands from the higher-level device, and 41
represents a mode specification bit.

Next, the operation of the storage subsystem configured in this way will be explained.

(1) When the removable storage medium 2 is mounted on the deck 12, the controller of the storage subsystem l! l is a mode in which read/write access is made to a storage area at an arbitrary address, like a magnetic disk (addressing mode), and a mode in which read/write access is made to a storage area at an arbitrary address, like in a magnetic tape device, and a mode in which the first storage area is accessed sequentially without specifying an address, like in a magnetic tape device. Reads the commutative notation medium control information setting area 21 in which one of the modes (sequential mode) for read/write access to the next information storage area position is set, and reads the control information setting area 21 in the control device. It is stored in the mode setting table 111 corresponding to each deck.

Note that this mode designation is performed by operating the panel switch 13.

As explained earlier, the control information in this control information setting area 21 includes the information of the storage information medium, the unused/existing valid data display bit, and the mode written at that time if there is existing valid data. Contains a bit to indicate
Unused mode setting table 111 for each deck/
It is stored in the presence of existing valid data indication bit 112 and the sequential mode/addressing mode indication bit 113.

(2) This mode designation can also be set by command 4 from the host device. That is, if the unused/existing valid data indicating bit in the control information of the removable storage medium indicates an unused state, it is set by command 4 from the host device, and Settings are also made in accordance with command 4 instructions, such as when discarding existing data and using the medium anew. For these determinations, the storage subsystem control unit 11 performs mode settings according to predetermined rules.

In this case, for example, the following operation is performed.

■The command that specifies the positioning is specified at the beginning of the command chain, and then the read/write (R
If an EAD/WRITE command is received, set the storage medium to sequential mode.

Direct reading/writing without specifying an address (READ/
WRITE) command, sets the addressing mode for the storage medium.

(2) When a dedicated command 4 is received for mode setting, the instruction of the mode designation bit 41 therein is followed.

Also, unused/existing valid data display bit 112
If there is existing valid data and there is a contradiction between the mode specified by the sequential mode/addressing mode display bit 113 and the instruction of the mode specification bit 41 of the upper command 4, subsequent operations are inhibited.

This makes it possible to protect existing data from erroneous operations and facilitate operational media management.

(3) When the addressing mode is specified, positioning is performed based on the instruction of the positioning command, and the subsequent read/write (READ/WRITE) command is executed. This behavior is.

This is similar to conventional magnetic disk devices and optical disk devices.

(4) If the sequential operation mode is specified, position to the 0th block is performed as an internal command.

Optical disk devices are rotating bodies, and if a command cannot be received while positioning is being performed (orientation is established), use the command retry function, etc. to complete positioning. At this point, the storage subsystem control unit 11 synchronizes so that the command can be received.

When the first read/write (READ/WRITE) access is completed, the control unit reads the address.

The block address is stored in the area 114 for storing the block address, and when the next access occurs, an internal command is used to instruct the positioning to the storage area immediately after this storage area.
Access this part.

Thereafter, addresses are stored sequentially and sequential operations similar to those of a magnetic tape device are performed.

Here, we have explained using a rewritable optical disk medium as an example of a removable storage medium, but any removable storage medium that can be read and written in a sequential mode and an addressing mode can be used. There is no particular limitation on the type of storage medium.

The present invention has been specifically explained above based on examples, but
It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof.

〔Effect of the invention〕

As described above, according to the storage subsystem of the present invention, the sequential mode and addressing mode can be set inside each storage medium, and the operation of each deck can be controlled based on the information. As a result, a sequential storage format that emphasizes storage bit cost and an addressing storage format that emphasizes random access performance can be realized using the same type of storage medium and within the same subsystem.

Furthermore, it is possible to eliminate the need to select a device according to the characteristics of each file, and to further unify operation and media management, thereby reducing operational costs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the overall schematic configuration of a storage subsystem according to an embodiment of the present invention. FIG. 2 is a detailed configuration diagram of the main parts of the system of FIG. 1. In the figure, 1... storage subsystem using a removable storage medium, 1! ...Storage subsystem control unit, 110...
Mode setting determination unit, 111...mode setting table,
112: Unused/presence of existing valid data indication bit, 113: Sequential mode/addressing mode indication bit, 114: Area for storing block addresses, 12: Deck group, 121 to 12N ...Each deck, 13...Panel switch, 2...Replaceable storage medium, 20...User storage area, 21...Control information setting area in the replaceable storage medium, 4... Command from host device, 41...Mode specification bit

Claims (1)

[Claims] (1) A removable disk storage medium that sequentially reads and writes data and reads and writes data by specifying an arbitrary address, a plurality of read/write devices that mount the storage medium, and control them. a first mode in which read/write access is made to a storage area at an arbitrary address in a storage subsystem comprising a control device;
A second mode is set in the removable medium in which read/write access is performed sequentially from the first storage area to the next information storage area without specifying an address; mode is specified, the storage area to be read and written is selected based on the instruction from the host device that specifies the access position, and if the second mode is specified, the storage medium is mounted. When the storage subsystem receives a read or write instruction for the same medium, the storage subsystem positions the storage area at the first storage area that can be written to, and positions the storage area at the next storage area each time a read or write instruction for the same medium is received.