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From: Paolo Bonzini <pbonzini@redhat.com>
To: Andrew Holway <a.holway@syseleven.de>
Cc: kvm@vger.kernel.org
Subject: Re: virtIO disks not usable
Date: Mon, 03 Sep 2012 08:41:31 +0200	[thread overview]
Message-ID: <5044511B.6090809@redhat.com> (raw)
In-Reply-To: <B2F0F75C-BC75-4E88-A6D7-EFF286FD4FD4@syseleven.de>

Il 31/08/2012 15:19, Andrew Holway ha scritto:
> I have 4096 block devices from sda..sdx.

Do you mean (here and in your other cache=none message) that the host
devices have 4k logical blocks?

If so, and if you use cache=none, you need to export them as 4k block
devices to the guest as well.  This is done with the
"logical_block_size=4096" sub-option in the "-device virtio-blk-pci"
command-line option.  Libvirt however does not support this yet.

Alternatively, there were QEMU-side patches to support emulating a
512-over-4k device (using read-modify-write).  One version I posted is
at http://lists.gnu.org/archive/html/qemu-devel/2011-12/msg01570.html --
I need to rebase and repost.

Paolo

      parent reply	other threads:[~2012-09-03  6:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-08-31 13:19 virtIO disks not usable Andrew Holway
2012-08-31 16:05 ` Andrew Holway
2012-09-03  6:41 ` Paolo Bonzini [this message]

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