SCSI persistent reservation: command not supported

[940607]

Hi.
I'm trying to build a virtual environment for a DB cluster that requires a shared SCSI device to support PR (persistent reservation) commands.

However, the reservations only work for iSCSI disks and don't work for VBox shareable disks. Compare:

Code: Select all

# SATA
[root@softiwarp-1 ~]# sg_persist --in --no-inquiry --read-reservation --device=/dev/sdc
PR in: command not supported
# SCSI BusLogic
[root@softiwarp-1 ~]# sg_persist --in --no-inquiry --read-reservation --device=/dev/sdd
PR in: command not supported
# iSCSI
[root@softiwarp-1 ~]# sg_persist --in --no-inquiry --read-reservation --device=/dev/sde
  PR generation=0x0, there is NO reservation held

[root@softiwarp-1 ~]# lsscsi
# SATA
[4:0:0:0]    disk    ATA      VBOX HARDDISK    1.0   /dev/sdc
# SCSI BusLogic
[5:0:0:0]    disk    VBOX     HARDDISK         1.0   /dev/sdd
# iSCSI
[6:0:0:0]    disk    LIO-ORG  shareddata       4.0   /dev/sde

Is there a workaround? I think iSCSI will be too slow.

[aeichner]

There is no workaround, this feature is not implemented and we don't have any plans to change that in the future. There is no demand from paying customers and it is a lot of work
to implement as it needs some communication channel between VMs for the synchronization. Patches are welcome though if they meet our coding standards