Storage Array Reservation Forwarding

Abstract

A method is provided for a destination storage system to handle SCSI-3 reservations. The method includes discovering a volume on a source storage system when the source storage system exports the volume to the destination storage system, exporting the volume to host computer systems, locally registering keys for first paths to the destination storage system, and registering with the source storage system the keys for second paths to the source storage system. When one of the host computer systems requests to reserve the volume, the method includes locally reserving the volume for paths to the destination storage system with registered keys and performing reservation forwarding to request the source storage system to reserve the volume for paths to the source storage system with registered keys.

1 - 20 . (canceled) 
     
     
         21 . A method performed by a destination storage system, comprising:
 discovering a volume that is accessible through a source storage system;   exporting the volume to a host computer system; and   receiving a request from the host computer system to reserve the volume while the host computer system is able to simultaneously access the volume via the destination storage system and the source storage system, and in response to the request:   locally reserving the volume for the host computer system; and   forwarding the reservation from the destination storage system to the source storage system by requesting the source storage system to reserve the volume for the destination storage system.   
     
     
         22 . The method of  claim 21 , comprising registering a key at the destination storage system for a path between the host computer system and the destination storage system, wherein the key comprises a SCSI-3 reservation key, and the volume is reserved with SCSI-3 reserve commands. 
     
     
         23 . The method of  claim 22 , comprising receiving a request to revoke the registered key, and in response to the request:
 locally revoking the registered key to prevent access to the volume via a path to the destination storage system associated with the registered key; and   sending a request from the destination storage system to the source storage system requesting the source storage system to revoke the registered key to prevent access to the volume via a path to the source storage system associated with the revoked key.   
     
     
         24 . The method of  claim 23 , comprising if an other host computer system requests to access the volume, determining that the request is along a path associated with a revoked key and reporting a reservation conflict back to the other host computer system. 
     
     
         25 . The method of  claim 21 , comprising receiving a request to access the volume, and if the request is along a path to the destination storage system associated with a registered key, requesting the source storage system to access the volume along the path to the source storage system associated with the registered key. 
     
     
         26 . The method of  claim 25 , comprising, if the source storage system reports a reservation conflict, reporting the reservation conflict back to the host computer system and locally revoking the registered key. 
     
     
         27 . The method of  claim 21 , comprising, prior to exporting the volume to the host computer system, admitting the volume on the destination storage system so the volume is exportable to the host computer system. 
     
     
         28 . A non-transitory computer-readable medium encoded with computer-readable instructions that, when executed by a processor of a destination storage system, direct the processor to:
 discover a volume that is accessible through a source storage system;   export the volume to a host computer system; and   receive a request from the host computer system to reserve the volume while the host computer system is able to simultaneously access the volume via the destination storage system and the source storage system, and in response to the request:   locally reserve the volume for the host computer system; and   forward the reservation from the destination storage system to the source storage system by requesting the source storage system to reserve the volume for the destination storage system.   
     
     
         29 . The medium of  claim 28 , comprising instructions that direct the processor to register a key at the destination storage system for a path between the host computer system and the destination storage system, wherein the key comprises a SCSI-3 reservation key, and the volume is reserved with SCSI-3 reserve commands. 
     
     
         30 . The medium of  claim 29 , comprising instructions that, in response to a request from a host computer system to revoke a registered key, direct the processor to:
 locally revoke the registered key to prevent access to the volume via a path to the destination storage system associated with the registered key; and   send a request from the destination storage system to the source storage system to request the source storage system to revoke the registered key to prevent access to the volume via a path to the source storage system associated with the revoked key.   
     
     
         31 . The medium of  claim 30 , comprising instructions that direct the processor to determine that the request is along a path associated with the revoked key and report a reservation conflict back to the other host computer system if an other host computer system requests to access the volume. 
     
     
         32 . The medium of  claim 28 , comprising instructions that, in response to a request to access the volume, direct the processor to:
 determine whether the request is along a path to the destination storage system associated with a registered key; and   if the request is along a path to the destination storage system associated with a registered key, requesting the source storage system to access the volume along the path to the source storage system associated with the registered key.   
     
     
         33 . The medium of  claim 32 , comprising instructions that direct the processor to report a reservation conflict to the host computer system and locally revoke the registered key in response to the source storage system reporting the reservation conflict. 
     
     
         34 . The medium of  claim 28 , comprising instructions that direct the processor to admit the volume on the destination storage system prior to exporting the volume to the host computer system so that the volume is exportable to the host computer system. 
     
     
         35 . A destination storage system, comprising:
 a network interface coupled to host computers and a source storage array;   a memory storing processor executable instructions; and   a processor to:
 discover a volume that is accessible through a source storage system; 
 export the volume to a host computer system; and 
 receive a request from the host computer system to reserve the volume while the host computer system is able to simultaneously access the volume via the destination storage system and the source storage system, and in response to the request: 
 locally reserve the volume for the host computer system; and 
 forward the reservation from the destination storage system to the source storage system by requesting the source storage system to reserve the volume for the destination storage system. 
   
     
     
         36 . The destination storage system of  claim 35 , comprising instructions that direct the processor to register a key at the destination storage system for a path between the host computer system and the destination storage system, wherein the key comprises a SCSI-3 reservation key, and the volume is reserved with SCSI-3 reserve commands. 
     
     
         37 . The destination storage system of  claim 36 , comprising instructions that, in response to a request from a host computer system to revoke a registered key, direct the processor to:
 locally revoke the registered key to prevent access to the volume via a path to the destination storage system associated with the registered key; and   send a request from the destination storage system to the source storage system to request the source storage system to revoke the registered key to prevent access to the volume via a path to the source storage system associated with the revoked key.   
     
     
         38 . The destination storage system of  claim 37 , comprising instructions that direct the processor to determine that the request is along a path associated with the revoked key and report a reservation conflict back to the other host computer system if an other host computer system requests to access the volume. 
     
     
         39 . The destination storage system of  claim 35 , comprising instructions that, in response to a request to access the volume, direct the processor to:
 determine whether the request is along a path to the destination storage system associated with a registered key; and   if the request is along a path to the destination storage system associated with a registered key, requesting the source storage system to access the volume along the path to the source storage system associated with the registered key.   
     
     
         40 . The destination storage system of  claim 39 , comprising instructions that direct the processor to report a reservation conflict to the host computer system and locally revoke the registered key in response to the source storage system reporting the reservation conflict.