[DRBD-user] Another iSCSI Active/Active Thread

Myles Gray myles.gray at exitex.com
Wed Oct 9 17:33:51 CEST 2013

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


I know that this has been discussed many times over by the community and Linbit engineers, however, is iSCSI active/active now safely deployable on DRBD using the built in kernel scsi target (LIO)?

I ask because it now supports VMWare's VAAI which is nothing more than a collection of t10 SCSI commands (it's not an API at all, why they called it that I don't know):

0x93    WRITE SAME(16)
0x41    WRITE SAME(10)
0x42    UNMAP
0x89    SCSI COMPARE and WRITE - ATS
0x83    EXTENDED COPY

The SCSI COMPARE AND WRITE command is used by clustering aware applications for resource locking, for example ESXi - therefore if your initiator is ESX's iSCSI Initiator and your target (LIO) supports VAAI then you can run active/active iSCSI on DRBD with no problems?

More on VAAI and SCSI Persistent Reservations:

http://www.quadstor.com/tech-library/134-high-availability-with-synchronous-mirroring.html

Myles

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