[stgt] [PATCH] release backing store when offline

James R. Leu jleu at inoc.com
Thu Jul 14 15:07:23 CEST 2011

Hello Tomonori,

It's hard to explain via email, but I will try.

We are building a geographically redundant SAN that will allow 
each LUN to be active on one node and passive on the other node
independent of the other LUNs.  To accomplish this we we
need to be able to mark a LUN as offline and have it release the
reference to the underlying block device so we can make it passive.
DRBD is doing the block level replication and asserts the notion
of active/passive.  It will not allow a block device to transition
to passive if anything is holding a reference to it.

The iSCSI clients of the SAN are geographically redundant as well.
The resources on those clients need to be able to migrate between the
datacenters independent of each other.  To accomplish this it is
highly desirable to keep the TGTD configuration nearly identical
on the nodes of the SAN so that the redundant iSCSI clients see
the same LUNs no matter if their local resources are active or passive.

If my patch does not appear to be anything you want in the
main distribution could you at least look it over to see if I am
overlooking anything?

Thank you

On Thu, Jul 14, 2011 at 02:06:26PM +0900, FUJITA Tomonori wrote:
> On Wed, 13 Jul 2011 11:12:26 -0500
> "James R. Leu" <jleu at inoc.com> wrote:
> > We have the need to be able to release the backing
> > store device when a target or LUN is marked as offline.
> Why do you want to do so?

James R. Leu
Software Architect
608.663.4555 fax
jleu at inoc.com

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