From: "Michael S. Tsirkin" <mst@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>,
Anthony Liguori <aliguori@us.ibm.com>,
linux-scsi <linux-scsi@vger.kernel.org>,
kvm-devel <kvm@vger.kernel.org>,
lf-virt <virtualization@lists.linux-foundation.org>,
Anthony Liguori <aliguori@linux.vnet.ibm.com>,
target-devel <target-devel@vger.kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
Zhi Yong Wu <wuzhy@cn.ibm.com>, Christoph Hellwig <hch@lst.de>,
Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Subject: Re: [RFC-v2 0/4] tcm_vhost+cmwq fabric driver code for-3.6
Date: Wed, 18 Jul 2012 19:00:15 +0300 [thread overview]
Message-ID: <20120718160015.GH1777@redhat.com> (raw)
In-Reply-To: <20120718155338.GA21817@infradead.org>
On Wed, Jul 18, 2012 at 11:53:38AM -0400, Christoph Hellwig wrote:
> On Wed, Jul 18, 2012 at 08:42:21AM -0500, Anthony Liguori wrote:
> >
> > If you add support for a new command, you need to provide userspace
> > a way to disable this command. If you change what gets reported for
> > VPD, you need to provide userspace a way to make VPD look like what
> > it did in a previous version.
> >
> > Basically, you need to be able to make a TCM device behave 100% the
> > same as it did in an older version of the kernel.
> >
> > This is unique to virtualization due to live migration. If you
> > migrate from a 3.6 kernel to a 3.8 kernel, you need to make sure
> > that the 3.8 kernel's TCM device behaves exactly like the 3.6 kernel
> > because the guest that is interacting with it does not realize that
> > live migration happened.
>
> I don't think these strict live migration rules apply to SCSI targets.
>
> Real life storage systems get new features and different behaviour with
> firmware upgrades all the time, and SCSI initiators deal with that just
> fine.
> I don't see any reason to be more picky just because we're
> virtualized.
Presumably initiators are shut down for target firmware upgrades?
With virtualization your host can change without guest shutdown.
You can also *lose* commands when migrating to an older host.
--
MST
next prev parent reply other threads:[~2012-07-18 16:00 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-11 21:15 [RFC-v2 0/4] tcm_vhost+cmwq fabric driver code for-3.6 Nicholas A. Bellinger
2012-07-11 21:15 ` [RFC-v2 1/4] vhost: Separate vhost-net features from vhost features Nicholas A. Bellinger
2012-07-11 21:15 ` Nicholas A. Bellinger
2012-07-11 21:15 ` [RFC-v2 2/4] vhost: make vhost work queue visible Nicholas A. Bellinger
2012-07-11 21:15 ` Nicholas A. Bellinger
2012-07-11 21:15 ` [RFC-v2 3/4] vhost: Add vhost_scsi specific defines Nicholas A. Bellinger
2012-07-11 21:15 ` Nicholas A. Bellinger
2012-07-11 21:15 ` [RFC-v2 4/4] tcm_vhost: Initial merge for vhost level target fabric driver Nicholas A. Bellinger
2012-07-11 21:15 ` Nicholas A. Bellinger
2012-07-17 15:05 ` [RFC-v2 0/4] tcm_vhost+cmwq fabric driver code for-3.6 Michael S. Tsirkin
2012-07-17 18:55 ` Anthony Liguori
2012-07-17 19:00 ` Michael S. Tsirkin
2012-07-17 21:50 ` Nicholas A. Bellinger
2012-07-18 13:42 ` Anthony Liguori
2012-07-18 13:42 ` Anthony Liguori
2012-07-18 13:56 ` Paolo Bonzini
2012-07-18 15:33 ` Michael S. Tsirkin
2012-07-18 15:53 ` Christoph Hellwig
2012-07-18 15:53 ` Christoph Hellwig
2012-07-18 16:00 ` Michael S. Tsirkin [this message]
2012-07-18 16:42 ` Rustad, Mark D
2012-07-18 17:17 ` Michael S. Tsirkin
2012-07-18 20:12 ` Rustad, Mark D
2012-07-18 20:12 ` Rustad, Mark D
2012-07-18 16:42 ` Rustad, Mark D
2012-07-18 16:00 ` Anthony Liguori
2012-07-18 16:00 ` Anthony Liguori
2012-07-18 16:47 ` James Bottomley
2012-07-18 19:12 ` Anthony Liguori
2012-07-19 6:00 ` Paolo Bonzini
2012-07-19 6:00 ` Paolo Bonzini
2012-07-19 7:28 ` James Bottomley
2012-07-19 7:30 ` Paolo Bonzini
2012-07-18 19:12 ` Anthony Liguori
2012-07-18 22:45 ` Nicholas A. Bellinger
2012-07-18 22:45 ` Nicholas A. Bellinger
2012-07-17 21:17 ` Nicholas A. Bellinger
2012-07-17 21:17 ` Nicholas A. Bellinger
2012-07-17 21:34 ` Michael S. Tsirkin
2012-07-17 22:02 ` Nicholas A. Bellinger
2012-07-17 22:02 ` Nicholas A. Bellinger
2012-07-17 22:18 ` Michael S. Tsirkin
2012-07-17 22:18 ` Michael S. Tsirkin
2012-07-17 22:37 ` Nicholas A. Bellinger
2012-07-17 23:11 ` Michael S. Tsirkin
2012-07-18 0:17 ` Nicholas A. Bellinger
2012-07-17 21:58 ` Michael S. Tsirkin
2012-07-17 22:04 ` Nicholas A. Bellinger
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