I/O accelerator for striped disk arrays using parity

Patent metadata

Field	Value
Publication number	US-10067682-B1
Application number	US-201615185522-A
Country	US
Kind code	B1
Filing date	Jun 17, 2016
Priority date	Apr 18, 2011
Publication date	Sep 4, 2018
Grant date	Sep 4, 2018

Abstract

Disclosed herein is an enhanced volume manager (VM) for a storage system that accelerates input/output (I/O) performance for random write operations to a striped disk array using parity. More specifically, various implementations are directed to accelerating “random writes” (writes comprising less than a complete stripe of data) by consolidating several random writes together to create a “sequential write” (a full-stripe write) to eliminate one or more read operations and/or increase the volume of new/updated data stored for each write operation. Several such implementations comprise functionality in the VM (volume manager) for identifying random write I/O requests, queuing them locally in a journal, and then periodically flushing the journal to the disk array as a sequential write request.

First claim

What is claimed is:

1. A non-transitory computer-readable medium having computer-executable instructions stored thereon for accelerating I/O performance for a striped-disk array that, when executed by a storage computer, cause the storage computer to:
receive a write I/O request directed to a portion of a stripe of the striped-disk array;
determine, prior to any forwarding of the received write I/O request to the striped-disk array, whether the write I/O request is random or sequential by comparing the write I/O request to a plurality of recent I/O requests;
in response to determining that the write I/O request is random, record the random write I/O request in a journal data storage area of the striped-disk array; and
periodically flush the journal data storage area by forming a sequential write I/O that spans a width of a stripe of the striped-disk array, the formed sequential write I/O comprising the random write I/O request and at least one other random write I/O request that is recorded in the journal data storage area.

2. The non-transitory computer-readable medium of claim 1 , having further computer-executable instructions stored thereon that, when executed by the storage computer, cause the storage computer to forward the sequential write I/O request to the striped-disk array in response to determining that the write I/O request is sequential.

3. The non-transitory computer-readable medium of claim 1 , having further computer-executable instructions stored thereon that, when executed by the storage computer, cause the storage computer to:
forward the formed sequential write I/O to the striped-disk array.

4. The non-transitory computer-readable medium of claim 3 , wherein the journal data storage area is periodically flushed in order to maintain a predetermined amount of storage capacity in the journal data storage area to accommodate incoming write I/O requests.

5. The non-transitory computer-readable medium of claim 3 , wherein the journal data storage area is periodically flushed at a time that minimizes impact on incoming I/O requests.

6. The non-transitory computer-readable medium of claim 1 , having further computer-executable instructions stored thereon that, when executed by the storage computer, cause the storage computer to:
maintain a journal table including a plurality of entries; and
in response to determining that the write I/O request is random, update an entry in the journal table corresponding to the random write I/O operation to indicate a location in the journal data storage area and the portion of the stripe of the striped-disk array to which the random write I/O request is directed.

7. The non-transitory computer-readable medium of claim 6 , having further computer-executable instructions stored thereon that, when executed by the storage computer, cause the storage computer to:
receive a read I/O request;
determine whether the journal table includes an entry corresponding to the read I/O request;
upon determining that the journal table includes an entry corresponding to the read I/O request, service at least a portion of the read I/O request from the journal data storage area; and
upon determining that the journal table does not include an entry corresponding to the read I/O request, forward the read I/O request to the striped-disk array.

8. The non-transitory computer-readable medium of claim 7 , having further computer-executable instructions stored thereon that, when executed by the storage computer, cause the storage computer to:
partition a storage capacity of the striped-disk array into zones;
maintain an accelerated zone table comprising entries that relate the zones to corresponding entries in the journal table;
determine a zone of the striped-disk array to which the read I/O request is directed; and
determine whether the journal table includes an entry corresponding to the read I/O request by searching the accelerated zone table based on the zone of the striped-disk array to which the read I/O request is directed.

9. A method for accelerating I/O performance for a striped-disk array, comprising:
receiving a write I/O request directed to a portion of a stripe of the striped-disk array;
determining, prior to any forwarding of the received write I/O request to the striped-disk array, whether the write I/O request is random or sequential by comparing the write I/O request to a plurality of recent I/O requests;
in response to determining that the write I/O request is random, recording the random write I/O request in a journal data storage area of the striped-disk array; and
periodically flushing the journal data storage area by forming a sequential write I/O that spans a width of a stripe of the striped-disk array, the formed sequential write I/O comprising the random write I/O request and at least one other random write I/O request that is recorded in the journal data storage area.

10. The method of claim 9 further comprising forwarding the sequential write I/O request to the striped-disk array in response to determining that the write I/O request is sequential.

11. The method of claim 9 further comprising:
forwarding the formed sequential write I/O to the striped-disk array.

12. The method of claim 11 , wherein the journal data storage area is periodically flushed in order to maintain a predetermined amount of storage capacity in the journal data storage area to accommodate incoming write I/O requests.

13. The method of claim 11 , wherein the journal data storage area is periodically flushed at a time that minimizes impact on incoming I/O requests.

14. The method of claim 9 , further comprising:
maintaining a journal table including a plurality of entries; and
in response to determining that the write I/O request is random, updating an entry in the journal table corresponding to the random write I/O operation to indicate a location in the journal data storage area and the portion of the stripe of the striped-disk array to which the random write I/O request is directed.

15. The method of claim 14 , further comprising:
receiving a read I/O request;
determining whether the journal table includes an entry corresponding to the read I/O request;
upon determining that the journal table includes an entry corresponding to the read I/O request, servicing at least a portion of the read I/O request from the journal data storage area; and
upon determining that the journal table does not include an entry corresponding to the read I/O request, forwarding the read I/O request to the striped-disk array.

16. The method of claim 15 , further comprising:
partitioning a storage capacity of the striped-disk array into zones;
maintaining an accelerated zone table comprising entries that relate the zones to corresponding entries in the journal table;
determining a zone of the striped-disk array to which the read I/O request is directed; and
determining whether the journal table includes an entry corresponding to the read I/O request further comprises searching the accelerated zone table based on the zone of the striped-disk array to which the read I/O request is directed.

17. A storage computer for accelerating I/O performance for a striped-disk array, comprising:
a processing unit; and
a memory communicatively connected to the processing unit that stores computer-executable instructions that, when executed by the processing unit, cause the storage computer to:
receive a write I/O request directed to a portion of a stripe of the striped-disk array;
determine, prior to any forwarding of the received write I/O request to t

Assignees

• American Megatrends Inc

Inventors

• Chatterjee Paresh
• Subramanian Srikumar
• Sowrirajan Raghavan
• Gopalakrishnan Sankarji

Classifications

• G06F2211/1066

  Parity-small-writes, i.e. improved small or partial write techniques in RAID systems · CPC title

• G06F3/0689

  Disk arrays, e.g. RAID, JBOD · CPC title

• G06F2211/1019

  Fast writes, i.e. signaling the host that a write is done before data is written to disk · CPC title

• G06F2211/104

  Metadata, i.e. metadata associated with RAID systems with parity · CPC title

• G06F2211/1038

  LFS, i.e. Log Structured File System used in RAID systems with parity · CPC title