Sharing disks between two kvm guests
Hi all,
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 ...
Many thanks.
Signature · 2 lines
CL Martinez
carlopmart {at} gmail {d0t} comQuoted 3 lines
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 ...
Have a look at KVM/QEMU's -smb option in http://bellard.org/qemu/qemu-doc.html
Quoted 6 lines · Felix Leimbach
Quoted 3 lines
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 ...Have a look at KVM/QEMU's -smb option in http://bellard.org/qemu/qemu-doc.html
Yes but this option doesn't helps me. I need to simulate a SAN ...
Signature · 2 lines
CL Martinez
carlopmart {at} gmail {d0t} comQuoted 7 lines · carlopmart
Quoted 6 lines · Felix Leimbach
Quoted 6 lines
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!
Signature · 1 line
Javier
Quoted 13 lines · Javier Guerra
Quoted 7 lines · carlopmart
Quoted 6 lines · Felix Leimbach
Quoted 6 lines
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.
Quoted 5 lines
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).
Any comments ?
Cheers,
Laurent
Signature · 3 lines
------------- [email protected] -------------- "In short: just say NO TO DRUGS and maybe you won't end up like the Hurd people." -- Linus Torvald
Quoted 40 lines · Laurent Vivier
Quoted 14 lines · Javier Guerra
Quoted 8 lines · carlopmart
Quoted 6 lines · Felix Leimbach
Quoted 6 lines
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.
Quoted 6 lines
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/nbd1and start two virtual hosts:
"qemu -hda v1.img -hdb
/dev/nbd0" and "qemu -hda v2.img -hdb/dev/nbd1"
Quoted 8 lines
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
Regards,
Anthony Liguori
Quoted 5 lines
Any comments ?
Cheers,
Laurent
Quoted 44 lines · Anthony Liguori
Quoted 43 lines · Laurent Vivier
Quoted 14 lines · Javier Guerra
Quoted 8 lines · carlopmart
Quoted 6 lines · Felix Leimbach
Quoted 6 lines
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.
Quoted 6 lines
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/nbd1and 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")
Quoted 7 lines
Quoted 5 lines
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".
Laurent
Quoted 11 lines
Regards,
Anthony Liguori
Quoted 5 lines
Any comments ?
Cheers,
Laurent
Signature · 3 lines
------------- [email protected] --------------- "The best way to predict the future is to invent it." - Alan Kay
Quoted 57 lines · Laurent Vivier
Quoted 55 lines · Anthony Liguori
Quoted 53 lines · Laurent Vivier
Quoted 17 lines · Javier Guerra
Quoted 10 lines · carlopmart
Quoted 7 lines · Felix Leimbach
Quoted 7 lines
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.
Quoted 7 lines
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/nbd1and 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).
Quoted 8 lines
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
Quoted 15 lines
Laurent
Quoted 12 lines
Regards,
Anthony Liguori
Quoted 6 lines
Any comments ?
Cheers,
Laurent
Quoted 10 lines · Javier Guerra
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!
This won't work with qcow images as metadata and allocation is not synchronized. Use raw images. cache=off is not strictly required, since the Linux pagecache will maintain coherency.
Signature · 2 lines
I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.