Managing data storage

• US 10,353,771 B1
• Filed: 03/31/2014
• Issued: 07/16/2019
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Original Assignee: Emc IP Holding Company LLC (Dell Technologies Inc.)
• Inventors: Cassano, Marc C., Foley, Robert P., Cummins, Daniel E., Heng, Socheavy D
• Primary Examiner(s): Blair, April Y
• Assistant Examiner(s): Gandhi, Dipakkumar B
• Application Number:
  US14/230,583
• Time in Patent Office: 1,933 Days
• CPC Class Codes: G06F 11/1076 Parity data used in redundant arrays of independent storages, e.g. in RAID systems

Abstract

There are disclosed computer-implemented methods, apparatus, and computer program products for managing data storage. In one embodiment, the computer-implemented method comprises the step of receiving new data to be written to storage. The method also comprises the step determining that the new data does not form a full stripe of data. The method also comprises reading missing non-parity data in the stripe of data. The method further comprises determining new parity based on the new data and the missing non-parity data. The method still further comprises writing the new data and the new parity to storage in a manner that does not require the missing non-parity data to be written to storage.

Claims

1. A computer-implemented method, comprising:

receiving a write request comprising new data to be written to a data storage system, wherein the data storage system comprises a plurality of data storage devices arranged in a redundant array of independent disk (RAID) group;

in response to receiving the write request, determining a size of the write request, wherein the size relates to a number of non-parity data portions in a full stripe of data that are associated with the new data;

based on the size of the write request, selecting one of a plurality of processes to implement storage of the new data; and

storing the new data in the RAID group in the data storage system in accordance with the selected process;

wherein the method is configured to select a first process when the size of the write request equates to less than half of the non-parity data portions in the full stripe of data, the first process comprising;

reading a parity and one or more non-parity data portions in the stripe of data associated with the new data,

calculating a new parity based on the parity and the one or more non-parity data portions and the new data, and

writing the new parity and the new data to the RAID group in the data storage system;

wherein the method is configured to select a second process when the size of the write request equates to half or more of the non-parity data portions in the full stripe of data but less than all of the non-parity data portions in the full stripe of data, the second process comprising;

reading a parity and one or more missing non-parity data portions in the full stripe of data,

verifying the coherency of the one or more missing non-parity data portions by comparing a checksum of the parity and a checksum of the one or more missing non-parity data portions,

determining a new parity based on the new data and the one or more missing non-parity data portions, and

writing, in response to verifying the coherency of the missing non-parity data portions, the new data and the new parity to the RAID group in the data storage system without writing the one or more missing non-parity data portions to the RAID group in the data storage system, wherein the new data and the new parity are written to the RAID group with a checksum;

wherein the method is configured to select a third process when the size of the write request equates to a full stripe of data, the third process comprising;

calculating a new parity based on the new data and writing the new parity and the new data to the RAID group in the data storage system.

2. An apparatus, comprising:

at least one processing device, said at least one processing device comprising a processor coupled to a memory;

wherein the apparatus is configured to;

receive a write request comprising new data to be written to a data storage system, wherein the data storage system comprises a plurality of data storage devices arranged in a redundant array of independent disk (RAID) group;

in response to receiving the write request, determine a size of the write request, wherein the size relates to a number of non-parity data portions in a full stripe of data that are associated with the new data;

based on the size of the write request, select one of a plurality of processes to implement storage of the new data; and

store the new data in the RAID group in the data storage system in accordance with the selected process;

wherein the apparatus is configured to select a first process when the size of the write request equates to less than half of the non-parity data portions in the full stripe of data, the first process comprising;

reading a parity and one or more non-parity data portions in the stripe of data associated with the new data,

calculating a new parity based on the parity and the one or more non-parity data portions and the new data, and

writing the new parity and the new data to the RAID group in the data storage system;

wherein the apparatus is configured to select a second process when the size of the write request equates to half or more of the non-parity data portions in the full stripe of data but less than all of the non-parity data portions in the full stripe of data, the second process comprising;

reading a parity and one or more missing non-parity data portions in the full stripe of data,

verifying the coherency of the one or more missing non-parity data portions by comparing a checksum of the parity and a checksum of the one or more missing non-parity data portions,

determining a new parity based on the new data and the one or more missing non-parity data portions, and

writing, in response to verifying the coherency of the missing non-parity data portions, the new data and the new parity to the RAID group in the data storage system without writing the one or more missing non-parity data portions to the RAID group in the data storage system, wherein the new data and the new parity are written to the RAID group with a checksum;

wherein the apparatus is configured to select a third process when the size of the write request equates to a full stripe of data, the third process comprising;

calculating a new parity based on the new data and writing the new parity and the new data to the RAID group in the data storage system.

3. A computer program product having a non-transitory computer-readable medium storing instructions, the instructions, when carried out by one or more processors, causing the one or more processors to perform a method of:

receiving a write request comprising new data to be written to a data storage system, wherein the data storage system comprises a plurality of data storage devices arranged in a redundant array of independent disk (RAID) group;

in response to receiving the write request, determining a size of the write request, wherein the size relates to a number of non-parity data portions in a full stripe of data that are associated with the new data;

based on the size of the write request, selecting one of a plurality of processes to implement storage of the new data; and

storing the new data in the RAID group in the data storage system in accordance with the selected process;

wherein the method is configured to select a first process when the size of the write request equates to less than half of the non-parity data portions in the full stripe of data, the first process comprising;

reading a parity and one or more non-parity data portions in the stripe of data associated with the new data,

calculating a new parity based on the parity and the one or more non-parity data portions and the new data, and

writing the new parity and the new data to the RAID group in the data storage system;

wherein the method is configured to select a second process when the size of the write request equates to half or more of the non-parity data portions in the full stripe of data but less than all of the non-parity data portions in the full stripe of data, the second process comprising;

reading a parity and one or more missing non-parity data portions in the full stripe of data,

verifying the coherency of the one or more missing non-parity data portions by comparing a checksum of the parity and a checksum of the one or more missing non-parity data portions,

determining a new parity based on the new data and the one or more missing non-parity data portions, and

writing, in response to verifying the coherency of the missing non-parity data portions, the new data and the new parity to the RAID group in the data storage system without writing the one or more missing non-parity data portions to the RAID group in the data storage system, wherein the new data and the new parity are written to the RAID group with a checksum;

wherein the method is configured to select a third process when the size of the write request equates to a full stripe of data, the third process comprising;

calculating a new parity based on the new data and writing the new parity and the new data to the RAID group in the data storage system.