Cache utilization to efficiently manage a storage system

Patent metadata

Field	Value
Publication number	US-9658965-B2
Application number	US-201514818940-A
Country	US
Kind code	B2
Filing date	Aug 5, 2015
Priority date	Sep 28, 2014
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

In an approach for managing a storage system, distribution of storage volumes among a plurality of storage controller groups may be adjusted dynamically or adaptively based on the current access hot degrees of respective storage volumes in the storage system. In this way, optimized distribution of storage volumes can be achieved without user interference. Such redistribution eliminates the degradation of performance of the storage system.

First claim

The invention claimed is:

1. A method for managing a storage system, the storage system including a plurality of storage controller groups and a plurality of storage volumes, each of the plurality of storage volumes being associated with one of the plurality of storage controller groups, the method comprising:
determining, by a computer processor, one or more cache occupation amounts of the plurality of storage volumes in the respective associated storage controller groups; and
generating, by the computer processor, a plan of redistribution of the plurality of storage volumes with respect to the plurality of storage controller groups by:
selecting, by the computer processor, a first one of the plurality of storage volumes which has a higher cache occupation amount than each other of the plurality of storage volumes and has not been redistributed;
determining, by the computer processor, respective one or more current cache free amounts of the plurality of storage controller groups;
selecting, by the computer processor, a first one of the plurality of storage controller groups which has a higher current cache free amount than each other of the plurality of storage controller groups for redistribution of the selected first one storage volume;
optimizing, by the computer processor, a plan of redistribution to reduce migration of the plurality of storage volumes among the plurality of storage controller groups, wherein the plurality of storage controller groups include a first storage controller group and a second storage controller group;

wherein the plurality of storage volumes comprise a first storage volume originally associated with the first storage controller group and a second storage volume originally associated with the second storage controller group, a cache occupation amount of the first storage volume being greater than a cache occupation amount of the second storage volume; and
wherein the optimizing the plan of redistribution comprises:
in response to the plan indicating that the first storage volume is to be migrated to the second storage controller group and the second storage volume is to be migrated to the first storage controller group, calculating a difference between the cache occupation amount of the first storage volume and the cache occupation amount of the second storage volume;
searching, by the computer processor, the plurality of storage volumes for a third storage volume associated with the first storage controller group, such that a cache occupation amount of the third storage volume matches the difference; and
in response to the third storage volume being found, modifying, by the computer processor, the plan such that the third storage volume is migrated to the second storage controller group, without migrating the first storage volume and the second storage volume between the first storage controller group and the second storage controller group.

2. The method according to claim 1 , wherein the selecting the first one of the plurality of storage volumes which has the higher cache occupation amount and has not been redistributed comprises selecting a storage volume that has not been redistributed from the plurality of storage volumes according to the one or more cache occupation amounts in a descending order, and wherein the selecting the first one of the plurality of storage controller groups which has the higher current cache free amount comprises: selecting one of the plurality of storage controller groups according to the one or more current cache free amounts in a descending order.

3. The method according to claim 1 , wherein the selecting the first one of the plurality of storage volumes which has the higher cache occupation amount and has not been redistributed comprises selecting from the plurality of storage volumes a storage volume that has a maximum cache occupation amount and has not been redistributed,
and wherein the selecting the first one of the plurality of storage controller groups which has the higher current cache free amount comprises selecting from the plurality of storage controller groups a storage controller group that has a maximum current cache free amount.

4. The method according to claim 1 , wherein the selecting the first one of the plurality of storage controller groups which has the higher current cache free amount comprises:
in response to that a first storage controller group and a second storage controller group of the plurality of storage controller groups have a same current cache free amount and that the selected storage volume is originally associated with the first storage controller group, selecting the first storage controller group.

5. The method according to claim 1 , wherein the plurality of storage controller groups include a first storage controller group, a second storage controller group and a third storage controller group;
wherein the plurality of storage volumes include a first storage volume originally associated with the first storage controller group and a second storage volume originally associated with the second storage controller group, a cache occupation amount of the first storage volume matching a cache occupation amount of the second storage volume; and
wherein the optimizing the plan of redistribution comprises:
in response to the plan indicating that the first storage volume is to be migrated to the second storage controller group and the second storage volume is to be migrated to the third storage controller group, modifying, by the computer processor, the plan such that the first storage volume is migrated to the third storage controller group, without migrating the second storage volume to the third storage controller group.

6. The method according to claim 1 , wherein the plurality of storage controller groups include a first storage controller group and a second storage controller group;
wherein the plurality of storage volumes comprise a first storage volume and a second storage volume which are originally associated with the first storage controller group; and
wherein the optimizing the plan of redistribution comprises:
in response to the plan indicating that the first storage volume and the second storage volume are to be migrated to the second storage controller group, searching, by the computer processor, the plurality of storage volumes for a third storage volume originally associated with the first storage controller group, such that a cache occupation amount of the third storage volume matching a sum of a cache occupation amount of the first storage volume and the second storage volume; and
in response to the third storage volume being found, modifying, by the computer processor, the plan such that the third storage volume migrated to the second storage controller group, without migrating the first storage volume and the second storage volume to the second storage controller group.

7. The method according to claim 1 , wherein the generating a plan of redistribution of the plurality of storage volumes with respect to the plurality of storage controller groups comprises:
monitoring, by the computer processor, cache utilization of at least one of the plurality of storage controller groups; and
triggering, by the computer processor, the plan of redistribution based on the monitored cache utilization.

8. The method according to claim 7 , wherein the monitoring cache utilization of at least one of the plurality of storage controller groups comprises:
determining, by the computer processor, respective one or more cache free amounts of the plurality of storage controller groups;
calculating, by the computer processor, an average cache free amount of the plurality of storage controller groups based on the one or more cache free amounts; and

Assignees

• IBM

Inventors

• Feng Yicheng
• Liao Jun
• Wang dan dan
• Xu ming jun
• Yin Wen Bao

Classifications

• G06F12/0873

  Mapping of cache memory to specific storage devices or parts thereof · CPC title

• G06F12/0806

  Multiuser, multiprocessor or multiprocessing cache systems · CPC title

• G06F12/0871 Primary

  Allocation or management of cache space · CPC title