Reducing I/O delays associated with snapshots using hints

A method of processing I/O operations comprising:

• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein first data is stored at the first location of the logical device, and a first snapshot of the logical device references the first data, and wherein the preprocessing for the first write I/O operation includes:
• allocating a new storage portion;
• copying the first data to the new storage location;
• and
• updating the first snapshot to reference the new storage location.

A method of processing I/O operations comprising:

• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein first data is stored at the first location of the logical device, and a first snapshot of the logical device references the first data, and wherein the first snapshot is linked to a second logical device exposed to the host.

A system comprising:

• one or more processors;
• and
• a memory comprising code stored thereon that, when executed by the one or more processors, performs a method of processing I/O operations comprising:
• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein the host sends I/Os to a plurality of front end directors of the data storage system and the first hint is sent to a first of the plurality of front end directors, wherein the first front end director has a lowest relative workload of the plurality of front end directors.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method of processing I/O operations comprising:

• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein the host sends I/Os to a plurality of front end directors of the data storage system and the first hint is sent to a first of the plurality of front end directors, wherein the first front end director has a lowest relative workload of the plurality of front end directors.

A system comprising:

• one or more processors;
• and
• a memory comprising code stored thereon that, when executed by the one or more processors, performs a method of processing I/O operations comprising:
• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein first data is stored at the first location of the logical device, and a first snapshot of the logical device references the first data, and wherein the preprocessing for the first write I/O operation includes:
• allocating a new storage portion;
• copying the first data to the new storage location;
• and
• updating the first snapshot to reference the new storage location.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method of processing I/O operations comprising:

• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein first data is stored at the first location of the logical device, and a first snapshot of the logical device references the first data, and wherein the preprocessing for the first write I/O operation includes:
• allocating a new storage portion;
• copying the first data to the new storage location;
• and
• updating the first snapshot to reference the new storage location.

A system comprising:

• one or more processors;
• and
• a memory comprising code stored thereon that, when executed by the one or more processors, performs a method of processing I/O operations comprising:
• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein first data is stored at the first location of the logical device, and a first snapshot of the logical device references the first data, and wherein the first snapshot is linked to a second logical device exposed to the host.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method of processing I/O operations comprising:

• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, wherein first data is stored at the first location of the logical device, and a first snapshot of the logical device references the first data, and wherein the first snapshot is linked to a second logical device exposed to the host.

A system comprising:

• one or more processors;
• and
• a memory comprising code stored thereon that, when executed by the one or more processors, performs a method of processing I/O operations comprising:
• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, and wherein the method further includes:
• determining that the logical device having at least one snapshot on the data storage system has a current I/O response time that has increased relative to a second I/O response time for I/Os directed to the logical device when the logical device had no associated snapshots.

A non-transitory computer readable medium comprising code stored thereon that, when executed, performs a method of processing I/O operations comprising:

• selecting a logical device having at least one snapshot on a data storage system;
• sending, from a host to the data storage system, a first hint for a first write I/O operation directed to a first location on the logical device, wherein said sending the first hint is performed prior to the host sending the first write I/O operation to the data storage system;
• and
• responsive to receiving the first hint regarding the first write I/O operation to the first location of the logical device having at least one snapshot, performing preprocessing for the first write I/O operation, and wherein the method further includes:
• determining that the logical device having at least one snapshot on the data storage system has a current I/O response time that has increased relative to a second I/O response time for I/Os directed to the logical device when the logical device had no associated snapshots.