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Re: [Linux-cluster] SCSI Reservations & Red Hat Cluster Suite



Tomasz Sucharzewski wrote:
Hello,

Ryan O'Hara wrote:
4  - Limitations
...
- Multipath devices are not currently supported.

What is the reason - it is strongly required to use at least two HBA in a SAN network, which is useless when using scsi reservation.


It has to do with how dm-multipath handles ioctls. In brief, the SCSI registration/reservation commands use ioctls, and those need to be passed to all devices within a dm-multipath target. This is required for getting SCSI reservations to work, since all the I/O paths need to be registered correctly.

I believe that this is only a limitation for RHEL4. RHEL5 should have a fix that allows dm-multipath to properly pass ioctls to all devices.

-Ryan


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