Data storing system and data transfer method

• US 5,606,706 A
• Filed: 08/22/1994
• Issued: 02/25/1997
• Est. Priority Date: 07/09/1992
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takamoto, Ken-ichi, Yoshida, Minoru, Takahashi, Naoya, Kogai, Makoto, Nakagoshi, Kazuo
• Primary Examiner(s): Bowler, Alyssa H.
• Assistant Examiner(s): FOLLANSBEE, JOHN A
• Application Number:
  US08/293,624
• Time in Patent Office: 918 Days
• Field of Search: 395/800, 395/600, 395/425, 395/575, 395/888, 395/441, 395/440, 395/182.04
• US Class Current: 711/100
• CPC Class Codes: G06F 11/1435 using file system or storage system metadata
• CPC Class Codes: G06F 12/0866 for peripheral storage systems, e.g. disk cache
• CPC Class Codes: G06F 2212/401 Compressed data

Abstract

The write data is entered from the upper unit into a nonvolatile cache provided in a controller inside of each disk unit through a channel adaptor, a cache shared by each disk, and a disk adaptor. The data from the cache is compressed by the data compressing and restoring device and is written in the disk. At a time, the management information for compressed data is written in the cache and the disk as well. In case of breaking the management information of the cache when a failure takes place in the cache memory, the management information is written for each disk. Hence, the breakage does not have an adverse effect on the other disks. If the management information of the cache is broken, the management information given into the disk may be replaced with the broken information.

Claims

1. A data storing system comprising:

a) a channel adaptor;

b) a disk adaptor coupled to said channel adaptor; and

c) more than two disk units coupled to a host computer through said channel adaptor and said disk adaptor each disk unit including;

(i) a disk controller having (a) a nonvolatile cache memory with a first storage area, and (b) a data compressing and restoring device compressing data read from the nonvolatile cache memory and generating management information for the compressed data; and

(ii) a disk having a second storage area for storing the management information for the compressed data stored therein, wherein said disk controller stores the management information in both the first and second storage areas;

d) means for outputting a first WRITE command for data stored in the large volume cache memory from the host computer to one disk unit of the more than two disk units through the disk adaptor;

e) means for transferring data stored in the large volume cache memory to one cache memory provided in the one disk unit, based on the first WRITE command;

f) means for notifying termination of transferring to the one cache memory to the disk adaptor;

g) means for outputting a second WRITE command for data stored in the large volume cache memory to another disk unit of the more than two disk units through the disk adaptor;

h) means for transferring data stored in the large volume cache memory to another cache memory provided in another disk unit, based on said second WRITE command;

i) means for notifying termination of transferring to another cache memory to the disk adaptor;

j) means for transferring the data stored in the one cache memory to one data compressing and restoring device to compress the data and generate first management information for the compressed data;

k) means for transferring the first management information to the one cache memory;

l) means for transferring the compressed data with the first management information to one disk;

m) means for transferring the data stored in another cache memory to another data compressing and restoring device to compress the data and generate second management information for the compressed data;

n) means for transferring the second management information to another cache memory; and

o) means for transferring the compressed data with the other management information to another disk independently regardless of transferring the compressed data to the one disk.

2. A data storing system comprising:

a) a channel adaptor;

b) a disk adaptor coupled to said channel adaptor; and

c) more than two disk units coupled to a host computer through said channel adaptor and said disk adaptor, each disk unit including;

(i) a disk controller having (a) a nonvolatile cache memory with a first storage area, and (b) a data compressing and, restoring device compressing data read from the nonvolatile cache memory and generating management information for the compressed data; and

(ii) a disk having a second storage area for storing the management information for the compressed data stored therein, wherein said disk controller stores the management information in both the first and second storage areas;

d) means for ouputting a first READ command for data stored in one disk provided in one disk unit of the more than two disk units from the host computer to the one disk unit through the disk adaptor;

e) means for transferring data stored in the one disk to one data compressing and restoring device;

f) means for restoring the data stored in the one disk to uncompressed data using management information stored in one cache memory in the one disk unit, or upon failure of the one cache memory using management information stored in the one disk;

g) means for outputting a second READ command for data stored another disk provided in another disk unit through the disk adaptor;

h) means for transferring data stored in another disk to another data compressing and restoring device;

i) means for restoring the data stored in another disk to uncompressed data using management information stored in another cache memory in another disk unit, or upon failure of another cache memory using management information stored in another disk in parallel to the restoring and transferring the data at one disk unit; and

j) means for transferring the data transferred to the one cache memos and another cache memory to the large volume memory in response to a predetermined order of said first and second READ commands.

3. In a data transfer method for transferring data between a large volume cache memory provided with a host computer and more than two disk units being coupled to a bus through a channel adaptor and a disk adaptor, said data transfer method comprising the steps of:

a) outputting a first WRITE instruction for data stored in said large volume cache memory from said host computer to a first disk unit through said channel adaptor and said disk adaptor;

b) transferring data stored in said large volume cache memory to a first cache memory provided in said ;

first disk unit, based on said first WRITE instruction, and notifying termination of transferring to said first cache memory to said disk adaptor;

c) outputting a second WRITE instruction for data stored in said large volume cache memory to a second disk unit through said disk adaptor;

d) transferring data stored in said large volume cache memory to a second cache memory provided in said second disk unit based on said second WRITE instruction, and notifying termination of transferring to said second cache memory to said disk adaptor;

e) transferring the data stored in said first cache memory to a first data compressing and restoring device to compress the data and generate first management information for the compressed data, transferring the first management information to said first cache memory, and transferring the compressed data with the first management information to a first disk;

f) transferring the data stored in said second cache memory to a second data compressing and restoring device to compress the data and generate second management information for the compressed data, transferring the second management information to said second cache memory, and transferring the compressed data with the second management information to a second disk independently regardless of transferring the compressed data to the first disk at the step e); and

g) storing the first and second management information necessary to restore the compressed data in the first and second nonvolatile cache memories, respectively, and in the first and second disks, respectively.

5. The method according to claim 3, wherein said step e) of transferring first management information further comprises transferring a head address, an end address and a compressed data length as the first management information.

4. In a data transfer method for transferring data between a large volume cache memory provided with a host computer and more than two disk units being coupled to a bus through a channel adaptor and a disk adaptor, said data transfer method comprising the steps of:

a) outputting a first READ instruction for data stored in a first disk provided in a first disk unit from said host computer to said first disk unit through said channel adaptor and said disk adaptor;

b) transferring data stored in said first disk to a first data compressing and restoring device and restoring the data stored in said first disk to uncompressed data using management information stored in a first cache memory in the first disk unit, or upon failure of the first cache memory using management information stored in the first disk;

c) outputting a second READ instruction for data stored in a second disk provided in a second disk unit to said second disk unit through said disk adaptor;

d) transferring data stored in said second disk to a second data compressing and restoring device and restoring the data stored in said second disk to uncompressed data using management information stored in a second cache memory in the second disk unit, or upon failure of the second cache memory using management information stored in the second disk in parallel to the restoring and transferring the data at the step b);

e) transferring the data transferred to said first cache memory and second cache memory to said large volume cache memory in response to a reading sequence of said first and second READ instruction to said large volume cache memory through said disk adaptor;

f) reading the first and second management information from the first and second nonvolatile cache memories;

g) upon failure of the first nonvolatile cache memory, reading the first management information from the first disk; and

h) upon failure of the second nonvolatile cache memory, reading the second management information from the second disk.

6. The method according to claim 4, wherein said step b) of restoring the data stored in the first disk further comprises using a head address, an end address and a compressed data length as the management information.

7. A data storing system for transferring data between a large volume cache memory provided with a host computer and more than two disk units being coupled to a bus through a channel adaptor and a disk adaptor, in which each disk unit includes a disk controller, a cache memory, a data compressing and restoring device and a disk, said data storing system comprising:

a) means for outputting a first WRITE command for data stored in the large volume cache memory from the host computer to one disk unit of the more than two disk units through the disk adaptor;

b) means for transferring data stored in the large volume cache memory to one cache memory provided in the one disk unit, based on the first WRITE command;

c) means for notifying termination of transferring to the one cache memory to the disk adaptor;

d) means for outputting a second WRITE command for data stored in the large volume cache memory to another disk unit through the disk adaptor;

e) means for transferring data stored in the large volume cache memory to another cache memory provided in another disk unit, based on said second WRITE command;

f) means for notifying termination of transferring to another cache memory to the disk adaptor;

g) means for transferring the data stored in the one cache memory to one data compressing and restoring device to compress the data and generate first management information for the compressed data;

h) means for transferring the first management information to the one cache memory;

i) means for transferring the compressed data with the first management information to one disk;

j) means for transferring the data stored in another cache memory to another data compressing and restoring device to compress the data and generate second management information for the compressed data;

k) means for transferring the second management information to another cache memory; and

l) means for transferring the compressed data with the other management information to another disk independently regardless of transferring the compressed data to the one disk.

8. A data storing system for transferring data between a large volume cache memory provided with a host computer and a plurality of n number of disk units being coupled to a bus through a channel adaptor and a disk adaptor, in which each disk unit includes a disk controller, a cache memory, a data compressing and restoring device and a disk, said data storing system comprising:

a) means for outputting a first READ command for data stored in one disk unit from the host computer to the one disk unit through the disk adaptor;

b) means for transferring data stored in the one disk to one data compressing and restoring device;

c) means for restoring the data stored in the one disk to uncompressed data using management information stored in one cache memory in the one disk unit, or upon failure of the one cache memory using management information stored in the one disk;

d) means for outputting a second READ command for data stored in another disk provided in another disk unit through the disk adaptor;

e) means for transferring data stored in another disk to another data compressing and restoring device;

f) means for restoring the data stored in another disk to uncompressed data using management information stored in another cache memory in another disk unit, or upon failure of another cache memory using management information stored in another disk in parallel to the restoring and transferring the data at the one disk unit; and

g) means for transferring the data transferred to the one cache memory and another cache memory to the large volume memory in response to a predetermined order of said first and second READ commands.

9. In a data transfer method for transferring data between a large volume cache memory provided with a host computer and more than two disk units being coupled to a bus through a channel adaptor and a disk adaptor, in which each of the disk units includes a disk controller, a cache memory, a data compressing and restoring device and a disk, said method comprising the steps of:

a) outputting a first WRITE commands for data stored in the large volume cache memory from the host computer to one disk unit through the disk adaptor;

b) transferring data stored in the large volume cache memory to one cache memory provided in the one disk unit, based on the first WRITE command;

c) notifying termination of transferring to the one cache memory to the disk adaptor;

d) outputting a second WRITE command for data stored in the large volume cache memory to one disk unit through the disk adaptor;

e) transferring data stored in the large volume cache memory to one cache memory provided in the one disk unit, based on the second WRITE command;

f) notifying termination of transferring to the one cache memory to the disk adaptor;

g) transferring the data stored in the one cache memory to one data compressing and restoring device to compress the data and generate first management information for the compressed data;

h) transferring the first management information to the one cache memory;

i) transferring the compressed data with the first management information to one disk;

j) transferring the data stored in the one cache memory to one data compressing and restoring device to compress the data and generate second management information for the compressed data;

k) transferring the second management information to the one cache memory; and

l) transferring the compressed data with the second management information to one disk independently regardless of transferring the compressed data to the one disk.

10. In a data transfer method for transferring data between a large volume cache memory provided with a host computer and more than two disk units being coupled to a bus through a channel adaptor and a disk adaptor, in which each disk unit includes a disk controller, a cache memory, a data compressing and restoring device and a disk, said method comprising the steps of:

a) outputting a first READ command for data stored in one disk provided in one disk unit from the host computer to the one disk unit through the disk adaptor;

b) transferring data stored in the one disk to one data compressing and restoring device;

c) restoring the data stored in the one disk to uncompressed data using first management information stored in one cache memory in the one disk unit, or upon failure of the one cache memory using first management information stored in the one disk;

d) outputting a second READ command for data stored in one disk provided in one disk unit through the disk adaptor;

e) transferring data stored in the one disk to one data compressing and restoring device;

f) restoring the data stored in the one disk to uncompressed data using second management information stored in one cache memory in the one disk unit, or upon failure of the one cache memory using second management information stored in the one disk in parallel to the restoring and transferring the data at the one disk unit; and

g) transferring the data transferred to the one cache memory and the one cache memory to the large volume memory in response to a predetermined order of first and second READ commands.