JPH11134252A - Information storage subsystem - Google Patents

Abstract

(57) [PROBLEMS] When performing a read request between a cache and a disk device, in the cache, what kind of pattern is the data not reflected (written) to the disk in the read data request range of the host. Even if the data exists, the performance must not be reduced by making a single data transfer request to the disk. SOLUTION: External storage device control unit 10 in the storage control unit
9 processes a read request from the host 100
According to the present invention, in addition to the normal data slot 114, a track corresponding to the track corresponding to the read request is temporarily stored in the cache 107 in accordance with the present invention. 115
Assign.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a host processing device such as a host computer (hereinafter referred to as a host computer or simply a host computer).
The present invention relates to a storage control unit connected to a host, and an information storage subsystem having an information storage unit composed of a disk device such as a magnetic disk storage device and an optical disk storage device. The present invention relates to an information storage subsystem adopting a data transfer control method for performing a process of reading data from an information storage unit to a cache in a storage control unit.

[0002]

2. Description of the Related Art When a host requests a disk storage device to specify a disk and its track and read out (read) information, an external storage device control unit in the storage control unit operates as disclosed in It is known that the following data transfer control is performed as disclosed in Japanese Patent Application Laid-Open No. 1-161551.

[0003] (1) All data within a range where a read request has been made from a higher-level host does not exist in a cache in a storage control unit.
In the case of a so-called cache miss, data transfer is requested to the disk storage device.

(2) In addition, some data within a range where a read request is made from a higher-level host is a cache miss, and some other data exists in a cache (cache hit).
And if there is a part that has not yet been reflected in the disk storage device in the cache hit data,
A request is made to transfer data to the disk storage device except for a data portion that has a cache hit and is not reflected in the disk storage device.

However, according to this control method, when the unreflected data portion is distributed to the disk device having a cache hit and exists in various patterns, the data is transferred to the disk device at a time with respect to the read request range of the upper host. If a data transfer request is issued, the data portion that has not been reflected on the disk device will be overwritten. Excluding, multiple times,
It is necessary to perform a data transfer request operation. For this reason, there is a disadvantage that the time required for disk rotation waiting and disk access increases.

[0006]

As described above, in the prior art, when a cache hit occurs but the data portion not reflected on the disk device is divided and exists in various patterns, the data is transmitted from the upper host. For the read request range, the data transfer request to the disk storage device is:
Except for the data portion that has not been reflected on the disk, the data is divided and a data transfer request is made a plurality of times, so that a disk rotation wait and a disk access time occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to reduce the rotational delay of a disk by making a single data transfer request to a disk within a read request range of a host, regardless of the data pattern on the cache. It is in.

[0008]

SUMMARY OF THE INVENTION In the prior art, the increase in disk rotation wait time and disk access time is caused by the data pattern of the cache, which causes the disk to be sent to the disk multiple times for the read request range of the host. This is because a data transfer request has been made.

Therefore, according to the present invention, when the external storage device control unit in the storage control unit processes a read request from an upper host, the external storage device control unit stores a normal data slot in a cache with respect to a track corresponding to the read request. Another feature of the present invention is that a "work slot" is temporarily assigned to the track separately from the data slot according to the present invention.

The data of the staged track is staged to the data slot side with respect to the cache miss portion of the data slot, and of the cache hit portion, the data portion that is not reflected in the disk storage device is The second feature is that staging to a work slot is performed. Thus, when the staging to the data slot and the work slot according to the present invention is completed. All data in the read request range from the upper host has a cache hit in either the data slot or the work slot.

According to a third feature of the present invention, the external storage device control unit in the storage control unit stores one disk storage device.
The data of the track staged as described above is sent to the normal slot for the cache miss portion. Further, by staging the data portion not reflected in the disk device in the cache to a work slot, the data transfer can be completed by one data transfer request without being affected by the data pattern of the cache, and the rotation of the disk can be completed. Waiting time and waiting time for disk access are reduced, and efficient data transfer can be realized.

According to the first to third features of the present invention, in the interface between the upper host and the storage controller, the read command of the upper host has the data requested to be read in the cache (cache hit). ), No (a cache miss), or an infinite number of data patterns, which are caused by whether the data has been reflected or not reflected in the disk device. The read data transfer at the interface with the device can be a single read transfer request and a data transfer operation in response thereto.

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the drawings.

[0014]

FIG. 1 shows the configuration of a disk subsystem according to an embodiment of the present invention. In FIG. 1, a disk control device 103 includes an optical communication control unit 104 that controls a communication protocol with a higher-level optical channel 101 connected to a higher-level device 100, an external storage device control unit 109 that controls a disk device 111, It comprises a channel control unit 106 that communicates with both, and a cache 107 that stores data. Each control unit has an optical fiber cable 1
01, an optical communication control unit / channel control unit bus 105, a channel control unit / external storage device control unit bus 108, an external storage device control unit / disk device bus 110,
The optical communication control unit / channel control unit / channel control unit / external storage device control unit 112 is connected by a bus 112.

The cache 107 has a data slot 114 for storing data and a work slot 115.

The optical communication control unit 104 has a buffer 113, and takes in write (write) data from the upper channel 101 or read (read) data from the channel control unit 106, and transfers the data to the buffer 113. I do. The data taken into the buffer 113 is transmitted to the channel control unit 10 by hardware control.
6 or transfer to the upper optical channel 101. The optical communication control unit 104 sends data write and read requests from the upper optical channel 101 to the channel control unit 106.
Notify to

The channel control unit 106 includes the optical communication control unit 1
Data transfer between the buffer 113 and the cache 107 is performed. The channel control unit 106 includes the optical communication control unit 10
4 to the external storage device control unit 109.

The external storage controller 109 reads data from the disk device 111 and stores it in the cache 107 (read). Data transfer in a staging operation, and reflects the data in the cache 107 to the disk device 111 (write). Perform staging data transfer. The external storage device control unit 109 notifies the channel control unit 106 that the data transfer between the cache 107 and the disk device 111 has been completed.

FIG. 2 is a flowchart showing a data transfer control operation between the cache disk and the external storage device control unit 109 according to the embodiment of the present invention. Less than,
The flow of the data transfer control operation between the cache and the disk by the external storage device control unit 109 will be described with reference to FIGS.

First, from the upper host, the optical channel 101
Through the disk controller 103 to the disk device 1
Track of a certain disk (for example, track 1
), And the channel control unit 1
At 06, an instruction to transfer data to track 1 of the disk of the disk device 111 and a data transfer control processing operation start (step 201).

Next, the monitoring process for a cache hit or cache miss is performed by checking whether or not the slot of track 1 has a cache hit in the cache (step 202).

In the case of a cache miss, only the data slot 114 is allocated as a slot of track 1 on the cache (step 203).

In the case of a cache hit, data hit / miss processing is entered, and it is first checked whether or not all data within the read request range exists in the cache (step 204).

If all the data exists in the cache, a data transfer completion notification is sent to the channel control unit 106 (step 210). enter.

In the process of allocating the work slot 115, the work slot 11 of the track 1 is stored in the cache.
5 (step 205).

Next, one data transfer request instruction is issued to the disk device 111 for the read request range (step 206).

Subsequently, the external storage device control unit 109 in the disk control device 103 starts a staging distribution process. In the staging distribution process, it is checked whether the data of track 1 staged from the disk device is a cache miss part (step 20).
7), the data of the cache miss portion is staged to the data slot 114 of the track 1 (step 20).
8) Also, the staged data is staged to the work slot 115 (step 20).
9).

When the staging is completed in this manner, all data in the read request range from the upper host exists in the cache, so that the external storage controller 109 sends the data to the channel controller 106. A transfer completion notification is made (step 210).

Finally, the work slot 115 is released (step 211), and the data transfer control operation is completed (step 212).

FIG. 3 shows a specific example of the data transfer control processing between the cache disk and the disk shown in FIG. 2 by a data structure. Hereinafter, an example of the data transfer control process of FIG. 3 will be described.

As a precondition, the disk device 111 is a magnetic disk device HDD, and data transfer from the HDD to the cache is performed in units of one track in the read request range.

FIG. 3A shows a case corresponding to step 203 in FIG. 2. Since all data in the read request range does not exist in the cache, data slot 1 in the cache is
14, one track (logical address space) in the read request range is allocated (step 311). From the HDD,
The data in the read request range is transferred from the track to the data slot 114 of the cache (step 31).
2).

FIGS. 3B to 3D show steps 2 and 3 of FIG.
A case corresponding to steps 04 to 208 is shown.

First, in FIG. 3B, for the data in the read request range from the upper host, a portion not reflected on the disk and a cache hit portion are distinguished (step 3).
21). In the figure, portions not reflected on the disk are indicated by dark shading, and cache hit portions are indicated by light shading. Note that, in the figure, the blank portion of the slot is a cache miss portion. Next, the unused (spare) area of the cache is allocated as a work slot to the track (logical address space) of the read request range on the cache (step 322). The allocated unused (spare) area is called a work slot.
This work slot assignment operation is performed in step 2 of FIG.
05.

Referring to FIG. 3C, the data transfer (read) request range from the disk of the HDD to the cache is set as the relevant track (step 323). The read request range is the D in the disk of the external storage device control unit 109 shown in FIG. 6B.
It is managed using the MA data transfer control information list table.

Further, in FIG. 3D, the data of the cache miss portion of the disk read request range is transferred from the track on the disk to the slot of the cache (step 324). This data transfer is managed using the in-cache DMA data transfer control information list table of the external storage device control unit 109 shown in FIG. 6C.

Further, the partial data of the disk read request range not reflected on the disk and the data of the cache part are transferred from the relevant track of the disk to the work slot of the cache (step 325). This data transfer is managed using the DMA data transfer control information list table to the work slot in the cache of the external storage device controller 109 shown in FIG. 6D.

Finally, the work slot area becomes an unused (spare) area of the cache, the data transferred to the work slot becomes invalid (unnecessary data) (step 326), and the work slot is released. This corresponds to step 211 in FIG.

FIG. 4 shows a cache DMA data transfer list information table of the external storage control unit 109. The cache DMA data transfer list information table 400 includes information for transferring the data of the cache miss portion of the read request range from the relevant track of the disk to the slot 114 in the cache, and the data portion of the read request range not reflected on the disk. And information for transferring data of the cache hit portion from the track on the disk to the work slot 115 in the cache.
Cache DMA data transfer list information table 400
Then, the slot pointer 401, the cache address 402, the target segment address 403, the offset value 404 in the slot, and the offset value 405 in the segment
And the transfer size 406.

Based on the cache DMA data transfer list information table 400, the read request portion and the work portion of the upper host are sorted in the cache as shown in the upper part of FIG.

FIG. 5 shows an in-disk DMA data transfer list information table. The in-disk DMA data transfer list information table 500 includes information for controlling the disk read request range, that is, the transfer request type (in this case, read) 501, the volume number 502, and the SC.
Each information of the SI block number 503 and the SCSI block number 504 is managed.

FIGS. 6A to 6D show in detail the data transfer control between the cache disk and the external storage controller.

First, FIG. 6A shows a logical address for one track on the cache in the read request range of the read command from the upper host. The logical address space for one track on the cache is divided into four segments (segments # 0, # 1, # 2, # 3). The slots in the cache within the read request range from the upper host include data that has not been reflected on the disk, and cache hits and cache misses of the data. Slot pointer # 1 indicates a cache slot pointer, and slot pointer # 2 indicates a cache work slot pointer. Addresses A, B, C, D, E, F, G,
H, I, and J indicate the addresses of the cache slots. The DMA data transfer list #, and the data transfer portion from the disk to the cache slot are shown. The DMA data transfer lists #, #, and # indicate the data transfer portion to the work slot. The read request range U indicates a read request range for the disk.

FIG. 6B shows an in-disk DMA data transfer control information list table of the external storage device controller. Using the in-disk DMA data transfer control information list table 600, one data transfer request is made for the data in the cache slot from the disk. In this case, the data transfer request type 601 is “read”, and the volume number 602 indicates volume #U.
For SCSI, SCSI block number #V, SC
The case where the number of SI blocks is #W is shown. The SCSI block number 603 indicates the number of the first SCSI block in the disk in which the data of the cache slot is present, and the SCSI block number 604 is the total number of SCSI blocks in the disk in which the data of the cache slot is present (one track). Is shown.

FIG. 6C shows a cache data slot data transfer control information list table of the external storage device controller. The data transfer control from the disk to the cache slot is performed using the cache data slot data transfer control information list table 600DS of FIG. 6C. That is, the cache miss portion is a data DMA data transfer list # from the disk to the cache.
,..., The data is transferred to the cache slot.

FIG. 6D shows a work slot data transfer control information list table 600WS in the cache of the external storage device controller. Work slot data transfer control information list table 600DS in cache of FIG. 6D
To control the data transfer from the disk to the work slot in the cache. That is, data not reflected on the disk and the cache hit portion of the data,.
Transfer data from the disk to the cache according to the data DMA transfer list #,.

[0047]

As described above, according to the present invention, when a read request is made between a cache and a disk device, the actual reflection to the disk within the range of the host's read data transfer request in the cache is performed. Regardless of the pattern in which the data exists, by completing a single data transfer request to the disk, the disk rotation waiting time is reduced, and the read request range from the upper host to the disk is reduced. There is an effect that the performance is not reduced by reducing the number of accesses or the number of accesses.

[Brief description of the drawings]

FIG. 1 is a block diagram of a disk subsystem.

FIG. 2 is a flowchart showing a data transfer control processing operation between a cache disk.

FIG. 3A shows the steps of FIG. 2; 9 is a flowchart of a data structure in a data transfer control operation when data of a track in a read request range does not cause a cache hit;

FIG. 3B is one of the steps of FIG. 9 is a flowchart of a data structure in a data transfer control operation when there is data that does not cause a cache hit in data in a read request range.

FIG. 3C is among the steps of FIG. 2; 9 is a flowchart of a data structure in a data transfer control operation when there is data that does not cause a cache hit in data in a read request range.

FIG. 3D is one of the steps of FIG. 2; 9 is a flowchart of a data structure in a data transfer control operation when there is data that does not cause a cache hit in data in a read request range.

FIG. 4 is a diagram showing the configuration and use of an in-cache DMA data transfer list information table of an external storage device control unit.

FIG. 5 is a diagram showing the configuration and use of an in-disk DMA data transfer control information list table of an external storage device control unit.

FIG. 6A is an explanatory diagram of logical addresses for one track on a cache in a read request range in details of cache disk-related data transfer control of the external storage device control unit.

FIG. 6B is a configuration diagram of an in-disk DMA data transfer control information list table of the external storage device control unit in details of cache disk-related data transfer control of the external storage device control unit.

FIG. 6C is a configuration diagram of a DMA data transfer control information list table to the data slot in the cache of the external storage device control unit in details of the cache disk data transfer control of the external storage device control unit.

FIG. 6D is a configuration diagram of a DMA data transfer control information list table for a work slot in a cache of the external storage device control unit, among details of the cache disk data transfer control of the external storage device control unit.

[Description of Reference Numerals] 101: upper optical channel, 102: optical fiber cable, 103: optical disk controller, 104: optical communication controller, 105: bus between optical communication controller and channel controller, 1
06 ... channel control unit, 107 ... cache, 108 ...
A bus between the channel control unit and the external storage device control unit;
External storage device control unit, 110: external storage device control unit / disk device bus, 111: disk device, 112: channel control unit / external storage device control unit / cache bus, 113: cache, 114: slot, 115 ...
Work slot

Claims (3)

[Claims] A storage control unit connected to a host processing device;
In an information storage subsystem having an information storage unit constituted by a disk device, the storage control unit includes a cache, and in response to a data read request from the higher-level device, a cache miss portion that does not exist in the cache is replaced by the information. An information storage subsystem, wherein the information is read from a storage unit to a data slot on a cache, and is divided into a read request part and a work part of the host processor in the cache. 2. A storage control unit connected to a host processor,
In an information storage subsystem having an information storage unit configured from a disk device, the storage control unit includes a cache, and in response to a data read request from the higher-level device, sets a data slot and a work slot in the cache, A cache miss portion that does not exist in the cache in the read request portion of the host processor is read from the information storage unit into the data slot on the cache, and data other than the cache miss portion in the read request portion of the host processor is read. An information storage subsystem for transferring data from the information storage part to the work slot and distributing the data in the cache into a read request part and a work part of the host processor. 3. A storage control unit connected to a host processor,
In an information storage subsystem having an information storage unit configured from a disk device, the storage control unit includes a cache, and, when receiving a read request command specifying a read request range from the higher-level processing device, converts the read request command to the read request command. An information storage subsystem characterized by determining data necessary for data creation according to the data, and receiving the necessary data from the information storage unit by one data transfer.