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List:       ceph-devel
Subject:    Re: ceph and scsi reservation-like locking
From:       Josh Durgin <josh.durgin () inktank ! com>
Date:       2013-12-30 21:43:14
Message-ID: 52C1E8F2.6060107 () inktank ! com
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On 12/28/2013 06:34 PM, James Harper wrote:
> Is the rbd locking feature-compatible with scsi3 persistent reservations?

It wasn't designed with scsi-3 exactly in mind, but using exclusive
locks and fencing might suffice.

To fence a client, you'd get its address from rbd_list_lockers() and
blacklist it with the 'ceph osd blacklist add' command, which can be
done via rados_mon_command() these days.

Blacklisting adds an entry in the osdmap so osds return an error when
blacklisted clients try to access them. By default a blacklist entry
expires after 1 hour.

> To use ceph as a storage backend for a Hyper-V cluster directly (rather than \
> through an iscsi gateway), it looks like I'll need a virtual scsi3 device that \
> supports persistent reservations.

I'm not sure exactly what parts of persistent reservations Hyper-V
relies on - let us know how it goes!

Josh
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