I/O accelerator for striped disk arrays using parity
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.
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 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.
18. The storage computer of claim 17 , wherein the memory stores further computer-executable instructions that, when executed by the processing unit, cause the storage computer to:
forward the formed sequential write I/O to the striped-disk array.
19. The storage computer of claim 17 , wherein the memory stores further computer-executable instructions that, when executed by the processing unit, cause the storage computer to:
maintain a journal table including a plurality of entries; and
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.
20. The storage computer of claim 19 , wherein the memory stores further computer-executable instructions that, when executed by the processing unit, 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.