System, method and a non-transitory computer readable medium for a pre-fetch operation
A method for pre-fetching information units, the method may include: (I) Receiving, by a storage system, write requests for writing information units to the storage system. Each write request includes a first identifier and a second identifier. The first identifier identifies a logical address. A combination of the first and second identifiers identifies an accessing entity that initiated the write request. (II) Receiving a read request for reading at least one information unit from the storage system, the read request is initiated by a certain accessing entity. (III) Determining whether to perform a pre-fetch of at least one additional information unit in response to at least one write request that was initiated by the certain accessing entity. If is determined to perform the pre-fetch then fetching the at least one additional information unit.
1. A method for pre-fetching information units, the method comprises:
receiving, by a storage system, write requests for writing information units to the storage system; wherein the write requests are initiated by multiple accessing entities;
wherein each write request comprises a first identifier and a second identifier;
wherein the first identifier identifies a logical address within a logical address space supported by the storage system and wherein a combination of the first and second identifiers identifies an accessing entity that initiated the write request;
receiving a read request for reading at least one information unit from the storage system, the read request is initiated by a certain accessing entity of the multiple accessing entities;
determining whether to perform a pre-fetch of at least one additional information unit in response to at least one write request that was initiated by the certain accessing entity, wherein the at least one write request forms a write request pattern initiated by the certain accessing entity; wherein the determining comprises comparing between (a) the write request pattern initiated by the certain accessing entity and (b) a read request pattern that comprises the read request initiated by the certain accessing entity; and
if it is determined to perform the pre-fetch then fetching the at least one additional information unit.
2. The method according to claim 1 , wherein the multiple accessing entities reside in a virtual environment hosted by the host computer.
3. The method according to claim 1 , wherein the write requests are initiated by multiple accessing entities of a group of host computers; wherein each host computer of the group of host computers hosts a virtual environment; wherein each first identifier of each write request further identifies a host computer of the group that hosts an accessing entity that initiated the write request.
4. The method according to claim 1 , wherein the determining comprises estimating whether the read request pattern at least partially matches the write request pattern initiated by the certain accessing entity.
5. The method according to claim 1 , wherein the multiple accessing entities comprise multiple guest operating systems and wherein the logical address space identified by the first identifier is a logical volume.
6. The method according to claim 1 , wherein the multiple accessing entities comprise a plurality of applications and wherein the logical address space identified by the first identifier is a logical volume.
7. The method according to claim 1 , wherein the second identifier is included in a small computer system interface (SCSI) compliant command.
8. The method according to claim 1 , comprising assigning, by the storage system, different values of the second identifier to different accessing entities of the multiple accessing entities.
9. The method according to claim 1 , comprising receiving, by the storage system, a mapping between different values of the second identifier and different accessing entities of the multiple accessing entities.
10. The method according to claim 1 , wherein the storage system comprises a cache memory and a group of disk drives; and wherein the pre-fetching comprises fetching the at least one additional information unit from at least one disk drive of the group to the cache memory.
11. A non-transitory computer readable medium that stores instructions for:
receiving write requests for writing information units to a storage system; wherein the write requests are initiated by multiple accessing entities; wherein each write request comprises a first identifier and a second identifier; wherein the first identifier identifies a logical address within a logical address space supported by the storage system and wherein a combination of the first and second identifiers identifies an accessing entity that initiated the write request;
receiving a read request for reading at least one information unit from the storage system, the read request is initiated by a certain accessing entity of the multiple accessing entities;
determining whether to perform a pre-fetch of at least one additional information unit in response to at least one write request that was initiated by the certain accessing entity, wherein the at least one write request forms a write request pattern initiated by the certain accessing entity; wherein the determining comprises comparing between (a) the write request pattern initiated by the certain accessing entity and (b) a read request pattern that comprises the read request initiated by the certain accessing entity; and
if is determined to perform the pre-fetch then fetching the at least one additional information unit.
12. The non-transitory computer readable medium according to claim 11 wherein the multiple accessing entities reside in a virtual environment hosted by the host computer.
13. The non-transitory computer readable medium according to claim 11 wherein the write requests are initiated by multiple accessing entities of a group of host computers; wherein each host computer of the group of host computers hosts a virtual environment; wherein each first identifier of each write request further identifies a host computer of the group that hosts an accessing entity that initiated the write request.
14. The non-transitory computer readable medium according to claim 11 that stores instructions for estimating whether the read request pattern at least partially matches the write request pattern initiated by the certain accessing entity.
15. The non-transitory computer readable medium according to claim 11 that stores instructions for assigning different values of the second identifier to different accessing entities of the multiple accessing entities.
16. The non-transitory computer readable medium according to claim 11 that stores instructions for receiving a mapping between different values of the second identifier and different accessing entities of the multiple accessing entities.
17. The non-transitory computer readable medium according to claim 11 that stores instructions for fetching the at least one additional information unit from at least one disk drive of a storage system of the group to a cache memory of the storage system.
18. A storage system that comprises: a storage system controller that is arranged to receive write requests for writing information units to a storage system; wherein the write requests are initiated by multiple accessing entities of a host computer; wherein each write request comprises a first identifier and a second identifier; wherein the first identifier identifies a logical address within a logical address space supported by the storage system and wherein a combination of the first and second identifiers identifies an accessing entity that initiated the write request; receive a read request for reading at least one information unit from the storage system, the read request is initiated by a certain accessing entity of the multiple accessing entities; determine whether to perform a pre-fetch of at least one additional information unit in response to at least one write request that was initiated by the certain accessing entity, wherein the at least one write request forms a write request pattern initiated by the certain accessing entity; wherein the storage system controller that is arranged to determine by comparing between (a) the write request pattern initiated by the certain accessing entity and (b) a read request pattern that comprises the read request initiated by the certain accessing entity; and if is determined to perform the pre-fetch then fetching the at least one additional information unit.