Laurent Vivier wrote:
Le vendredi 20 juin 2008 à 11:37 -0500, Anthony Liguori a écrit :
Laurent Vivier wrote:
Le vendredi 20 juin 2008 à 09:07 -0500, Javier Guerra a écrit :
On Fri, Jun 20, 2008 at 7:23 AM, carlopmart <[EMAIL PROTECTED]> wrote:
Felix Leimbach wrote:
This is my first post to this list. I have already installed kvm-70
under rhel5.2. My intention is to share on disk image betwwen two rhel5.2
kvm guests. Is it possible to accomplish this in kvm like xen or vmware
does?? How can I do?? I didn't find any reference abou this on kvm
documentation ...
i tried this looong ago and didn't really work because there was some
userspace cache on each QEMU instance. but the -drive option has a
'cache=off' setting that should be enough.
in theory (i haven't tested, but Avi 'blessed' it):
- create a new image with qemu-img
- add it to the command line using -drive file=xxx,cache=off on both
KVM instances
- use a cluster filesystem!
RFC:
Well, well, perhaps it is delusions of a sick mind but since the
introduction of qemu-nbd I think we can develop easily something to
share a disk between several virtual hosts:
I- in a first step, we can modify qemu-nbd to accept several connections
for one disk image, for instance:
# qemu-nbd my-disk.qcow2
# nbd-client localhost 1024 /dev/nbd0
# nbd-client localhost 1024 /dev/nbd1
and start two virtual hosts:
"qemu -hda v1.img -hdb /dev/nbd0" and "qemu -hda v2.img -hdb /dev/nbd1"
Of course the filesystem must know how to share the access to the disk
with others (-> "cluster filesystem")
II- in a second step, we can include directly the nbd protocol in qemu
(block-nbd.c, "-drive file=nbd:localhost:1024") to connect to the
server. We can also add some commands to the protocol to manage lock,
HA, "what else ?" (Hi George).
http://hg.codemonkey.ws/qemu-pq/file/25ca451f2040/block-nbd.diff
You're not fun, Anthony.
Perhaps, now, it should be better if you use functions defined in the
(new) file "nbd.c".
That patch is very old by now. It needs to be updated/written to use
the aio infrastructure which will be a little tough since there are some
assumptions right now that all aio is posix-aio.
Regards,
Anthony Liguori
Laurent
Regards,
Anthony Liguori
Any comments ?
Cheers,
Laurent
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