From: Paolo Bonzini <pbonzini@redhat.com>
To: Chen HanXiao <chenhanxiao@cn.fujitsu.com>
Cc: 'Christoph Hellwig' <hch@lst.de>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] Use SCSI command to get size of SG device
Date: Wed, 10 Oct 2012 11:01:31 +0200 [thread overview]
Message-ID: <5075396B.2060302@redhat.com> (raw)
In-Reply-To: <006501cda6c1$e080f8a0$a182e9e0$@cn.fujitsu.com>
Il 10/10/2012 10:33, Chen HanXiao ha scritto:
>> You need to use scsi-block instead of scsi-generic. However, I don't see
>> how this can work. After the snapshot, the image will be qcow2, not raw, and
>> thus it will not support bdrv_aio_ioctl. Hence any SCSI command (for
>> scsi-generic) or any non-data SCSI command (for scsi-block) will fail.
>
> That's the issue what I also encountered.
> Do you mean that it is impossible for us to enable snapshot for
> scsi-generic?
It's impossible, and rightly so: the user could anyway bypass the
snapshotting and write to the disk (WRITE SAME for example).
Not just snapshot=on, which fails because it is early enough that the
disk fails to initialize. Live snapshots also ought to be blocked, it
is a bug that they are not.
Paolo
prev parent reply other threads:[~2012-10-10 9:01 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-09 9:42 [Qemu-devel] [PATCH] Use SCSI command to get size of SG device Chen HanXiao
2012-10-09 17:21 ` Christoph Hellwig
2012-10-10 2:11 ` Chen HanXiao
2012-10-10 6:33 ` Paolo Bonzini
2012-10-10 8:33 ` Chen HanXiao
2012-10-10 9:01 ` Paolo Bonzini [this message]
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