[Linux-cluster] SCSI 2 vs SCSI 3 reservation

[Maciej Bogucki]

Sadek, Abdel napisał(a):
> Is there a document that clearly explains the difference between SCSI 2
> reserve/release and SCSI 3 persistent reservation?
> 
Google->"SCSI-2  SCSI-3 persistent reservation" fe. [1]

> My understanding of the SCSI reservation in a Cluster environment is
> that one node Only can reserve a LUN for write access.

No. For SCSI-3 PR only one node can reserve device but alle registrant
could have access to write - it depends also which mode for PROUT type
You set(fe. write exclusive - registrants only) [2]
> 
> In my 2 node RHEL 4.5 cluster I’ve noticed that both nodes are
> registered with my LUNs from my SAN storage array. Only one of them
> holds the reservation but both can access it for Read/Writes.

It is ok. For SCSI-3 PR all nodes could do registration, but only one
could have reservation.


[1] - http://blogs.sun.com/kristien/entry/scsi_reservations_in_sun_cluster
[2] - http://t10.org/ftp/t10/document.03/03-230r1.pdf

Best Regards
Maciej Bogucki