Storage virtualization apparatus and storage virtualization method

A method for making a plurality of storage devices function as one or more virtual volumes, a first storage virtualization apparatus connected with a plurality of storage ports with the plurality of storage devices executing:

• storing, with respect to each of the plurality of storage ports, a process incomplete command count defined as number of commands that are not yet processed by the storage device having each storage port into a first storing unit;
• obtaining, from each storage virtualization apparatus connected to any one of the plurality of storage ports, the process incomplete command count accumulated by the storage virtualization apparatus, and storing into a second storing unit, with respect to each of the plurality of storage ports, a process incomplete command total count that is a total of the process incomplete command count obtained from each of other storage virtualization apparatuses and the process incomplete command count obtained from the first storing unit;
• and
• obtaining, when receiving an access request against any one of the plurality of storage devices, the process incomplete command total count about a storage port corresponding to the received access request from the second storing unit, and causing, when the obtained process incomplete command total count is larger than a prescribed number, completion timing of an access responding process to the access request to be delayed.

A non-transitory computer readable medium storing a program for causing the computer connected with a plurality of storage ports of a plurality of storage devices to execute a process, the process comprising:

• storing, with respect to each of the plurality of storage ports, a process incomplete command count defined as number of commands that are not yet processed by the storage device having each storage port into a first storing unit;
• obtaining, from each storage virtualization apparatus connected to any one of the plurality of storage ports, the process incomplete command count accumulated by the storage virtualization apparatus, and storing into a second storing unit, with respect to each of the plurality of storage ports, a process incomplete command total count that is a total of the process incomplete command count obtained from each of other storage virtualization apparatuses and the process incomplete command count obtained from the first storing unit;
• and
• obtaining, when receiving an access request against any one of the plurality of storage devices, the process incomplete command total count about a storage port corresponding to the received access request from the second storing unit, and causing, when the obtained process incomplete command total count is larger than a prescribed number, completion timing of an access responding process to the access request to be delayed.

A storage virtualization apparatus cluster for making a plurality of storage devices function as one or more virtual volumes, the cluster comprising:

• a first storage virtualization apparatus and one or more second storage virtualization apparatus each of which is connected with a plurality of storage ports across the plurality of storage devices;
• the first storage virtualization apparatus including:
• an accumulate unit to accumulate, with respect to each of the plurality of storage ports, a process incomplete command count defined as number of commands that are sent by the first storage virtualization apparatus, but are not yet processed by the storage device having each storage port;
• a management unit to periodically obtain, from each of other storage virtualization apparatuses connected to any one of the plurality of storage ports, the process incomplete command count accumulated by the storage virtualization apparatus, calculates, with respect to each of the plurality of storage ports, a process incomplete command total count that is a total of the process incomplete command count obtained from each of the other storage virtualization apparatuses and the process incomplete command count accumulated by the accumulate unit, sends the calculated process incomplete command total counts to each of the second storage virtualization apparatus and manages the calculated process incomplete command total counts;
• and
• an access request responding unit to perform, when receiving an access request against any one of the plurality of storage devices from a server, an access responding process including a process of issuing a command to a storage port corresponding to the access request,
• wherein the access request responding unit, when the process incomplete command total count about the storage port corresponding to the access request managed by the management unit is larger than a prescribed number, delays completion timing of an access responding process to the access request,
• each of the one or more second storage virtualization apparatus including:
• a second accumulate unit to accumulate, with respect to each of the plurality of storage ports, the process incomplete command count defined as number of commands that are sent by the second storage virtualization apparatus, but are not yet processed by the storage device having each storage port;
• a sending unit to send the process incomplete command count about each storage port to the first storage virtualization apparatus;
• a second management unit to manage the process incomplete command total count about each storage port that is sent from the first storage virtualization apparatus;
• a second access request responding unit to, when receiving an access request against any one of the plurality of storage devices, obtain the process incomplete command total count corresponding to the received access request from the second storing unit, and to, when the obtained process incomplete command total count is larger than a prescribed number, cause completion timing of an access responding process to the access response to be delayed;
• and
• a second access request responding unit to perform, when receiving an access request from a server, an access responding process including a process of issuing a command to a storage port corresponding to the access request,
• wherein the second access request responding unit, when the process incomplete command total count about the storage port corresponding to the access request managed by the second management unit is larger than the prescribed number, delays completion timing of the access responding process to the access request.