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Re: [Qemu-devel] Question on virtio disk maximum index and maximum parti
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From: |
Richard W.M. Jones |
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Subject: |
Re: [Qemu-devel] Question on virtio disk maximum index and maximum partition |
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Date: |
Tue, 14 Jun 2011 13:27:15 +0100 |
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User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Wed, Jun 01, 2011 at 05:56:02AM +0100, Stefan Hajnoczi wrote:
> Partitions are not at the virtio-blk level. The guest operating
> system will see the virtio-blk disk and scan its partition table to
> determine which partitions are available. The limit then depends on
> the partitioning scheme that you use (legacy boot record, GPT, etc).
But practically the Linux virtio implementation imposes a limit of 15
partitions (vda + vda1 .. vda15 = 16), since it encodes the partition
number in 4 bits. If you have a virtio disk with more than 15
partitions, Linux guests will ignore the extra partitions. This may
or may not matter, but it's worth considering.
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines. Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v