Techniques for host to host transfer of sequential media and use of persistent reservation to protect media during host to host transfer
Techniques for host to host transfer of media and the use of persistent reservation to protect media during host to host transfer is disclosed. Exemplary embodiments may be realized as methods and systems for transferring a sequential media loaded in a drive from a first host to a second host without physically unloading the media. The first host may have a persistent reservation or non-persistent reservation of the drive. Likewise, the second host may have a persistent reservation or non-persistent reservation of the drive. Logical unload, logical load and preemption commands are utilized as is error recovery from a failed reservation.
1. A method operable in a controlling server for transferring a media loaded in a drive from a first host to a second host, wherein the first host comprises a non-persistent reservation of the drive, the method comprising:
sending a logical unload command instructing the first host to logically unload the media and release the non-persistent reservation;
determining if the second host will establish a non-persistent reservation or persistent reservation of the drive;
sending a logical load command instructing the second host to logically load the media, wherein the media is transferred from the first host to the second host without physically unloading or loading the media; and
generating a key for use by the second host in establishing the persistent reservation in the event it is determined that the second host will establish the persistent reservation of the drive, wherein the key comprises an allocation index associated with a drive/media coupling.
2. The method of claim 1 , wherein if it is determined that the second host will establish the non-persistent reservation, the logical load command further comprises an instruction to establish the non-persistent reservation of the drive.
3. The method of claim 1 , the logical load command further comprises an instruction for the second host to establish the persistent reservation of the drive using the generated key.
4. The method of claim 3 , wherein the key comprises an identifier of the drive and an identifier of the host.
5. The method of claim 1 , wherein the persistent reservation comprises a SCSI persistent reservation.
6. The method of claim 1 , wherein the media comprises sequential media.
7. The method of claim 6 , wherein the sequential media comprises magnetic media.
8. At least one non-transitory processor readable storage medium storing a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 1 .
9. A method operable in a controlling server for transferring a sequential media loaded in a drive from a first host to a second host, wherein the first host comprises a persistent reservation of the drive, the method comprising:
sending a logical unload command instructing the first host to logically unload the media and retain the persistent reservation;
determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and
sending a logical load command instructing the second host to logically load the media, wherein the media is transferred from the first host to the second host without physically unloading or loading the media; and
generating a key for use by the second host in establishing the persistent reservation in the event it is determined that the second host will establish the persistent reservation of the drive, wherein each of the key of the first host and the generated key of the second host further comprises an allocation index associated with a drive/media coupling.
10. The method of claim 9 , wherein if it is determined that the second host will establish the non-persistent reservation, instructing the first host to release the persistent reservation.
11. The method of claim 10 , wherein the logical load command further comprises an instruction to the second host to establish the reservation of the drive.
12. The method of claim 9 , further comprising sending a preemption command to the second host instructing the second host to preempt the persistent reservation of the first host, the preemption command comprising a key of the first host and the generated key of the second host.
13. The method of claim 12 , wherein each of the key of the first host and the generated key of the second host comprises an identifier of the drive and an identifier of the host.
14. The method of claim 9 , wherein the persistent reservation comprises a SCSI persistent reservation.
15. The method of claim 9 , wherein the media comprises sequential media.
16. The method of claim 15 , wherein the sequential media comprises magnetic media.
17. At least one non-transitory processor readable storage medium storing a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 9 .
18. A method operable in a controlling server for error recovery from a failed persistent reservation, the method comprising the following computer implemented steps:
receiving an error message from a host comprising a key held by a drive for a persistent reservation;
determining if the key was generated by a controlling server; and
controlling a recovery of the drive if the key was generated by the controlling server, wherein controlling the recovery of the drive comprises sending a command to preempt the persistent reservation of the drive, wherein controlling the recovery of the drive further comprises:
generating another key;
sending the command to the host or another host instructing the host or another host to preempt the persistent reservation of the drive using the generated another key and to physically unload a media from the drive.
19. The method of claim 18 , wherein the key comprises at least two of a drive identifier, host identifier, and drive/media coupling allocation index identifier.
20. The method of claim 18 , wherein determining if the key was generated by the controlling server, comprises:
determining if at least one portion of the key matches at least one of drive identifier, host identifier, and media allocation index identifier stored by the controlling server.
21. At least one non-transitory processor readable storage medium storing a computer program of instructions configured to be readable by at least one processor for instructing the at least one processor to execute a computer process for performing the method as recited in claim 18 .
22. A system for transferring a media loaded in a drive from a first host to a second host, wherein the first host comprises a non-persistent reservation of the drive, the system comprising:
means for sending a logical unload command instructing the first host to logically unload the media and release the non-persistent reservation;
means for determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and
means for sending a logical load command instructing the second host to logically load the media, wherein the media is transferred from the first host to the second host without physically unloading or loading the media; and
means for generating a key for use by the second host in establishing the persistent reservation in the event it is determined that the second host will establish the persistent reservation of the drive, wherein the key comprises an allocation index associated with a drive/media coupling.
23. A system for transferring a media loaded in a drive from a first host to a second host, wherein the first host comprises a persistent reservation of the drive, the system comprising:
means for sending a logical unload command instructing the first host to logically unload the media and retain the persistent reservation;
means for determining if the second host will establish a non-persistent reservation or persistent reservation of the drive; and
means for sending a logical load command instructing the second host to logically load the media, wherein the media is transferred from the first host to the second host without physically unloading or loading the media; and
means for generating a key for use by the second host in establishing the persistent reservation in the event it is determined that the second host will establish the persistent reservation of the drive, wherein each of the key of the first host and the generated key of the second host further comprises an allocation index associated with a drive/media coupling.
24. A system for error recovery from a failed persistent reservation comprising:
means for receiving an error message from a host comprising a key held by a drive for a persistent reservation;
means for determining if the key was generated by a controlling server; and
means for controlling a recovery of the drive if the key was generated by the controlling server, wherein controlling the recovery of the drive comprises sending a command to preempt the persistent reservation of the drive, wherein the means for controlling the recovery of the drive further comprises:
means for generating another key;
means for sending the command to the host or another host instructing the host or another host to preempt the persistent reservation of the drive using the generated another key and to physically unload a media from the drive.