I/O accelerator for striped disk arrays using parity
View Patent ↗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 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 sequential, forwarding the write I/O request to the striped-disk array; and
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;
periodically flushing the journal data storage area by forming a sequential write I/O comprising the random write I/O request and at least one other random write I/O request recorded in the journal data storage area that is directed to the stripe of the striped-disk array; and
forwarding the formed sequential write I/O to the striped-disk array.
2. The method of claim 1 , 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 random write I/O requests.
3. The method of claim 1 , wherein the journal data storage area is periodically flushed at a time that minimizes impact on incoming I/O requests.
4. The method of claim 1 , further comprising:
maintaining a journal table including a plurality of entries; and
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.
5. The method of claim 4 , 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.
6. The method of claim 5 , 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.
7. 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 sequential, forward the write I/O request to the striped-disk array; and
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;
periodically flush the journal data storage area by forming a sequential write I/O comprising the random write I/O request and at least one other random write I/O request recorded in the journal data storage area that is directed to the stripe of the striped-disk array; and
forward the formed sequential write I/O to the stripe-disk array.
8. The non-transitory computer-readable medium of claim 7 , 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 random write I/O requests.
9. The non-transitory computer-readable medium of claim 7 , wherein the journal data storage area is periodically flushed at a time that minimizes impact on incoming I/O requests.
10. 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:
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.
11. The non-transitory computer-readable medium of claim 10 , 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.
12. The non-transitory computer-readable medium of claim 11 , 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.
13. 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 sequential, forward the write I/O request to the striped-disk array; and
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;
periodically flush the journal data storage area by forming a sequential write I/O comprising the random write I/O request and at least one other random write I/O request recorded in the journal data storage area that is directed to the stripe of the striped-disk array; and
forward the formed sequential write I/O to the stripe-disk array.
14. The storage computer of claim 13 , 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.
15. The storage computer of claim 14 , 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.