Re: [Libvir] storage API and ZFS
On Thu, Oct 18, 2007 at 06:58:38PM +0100, John Levon wrote:
Accidentally deleted your reply Richard, sorry.
ZFS 'pools' are aggregates composed of some number of real devices. LVM
confuses me so I don't know what they map on to, but the basic idea is
that you can carve filesystems out of such pools at will.
That is the same concept as an LVM volume group.
You can also carve out 'volumes' - these appear as a disk
device in
/dev/zvol/dsk/poolname/volumename
That is the same concept as an LVM logical volume
It's the latter that you use in Xen to hold domU root filesystems
(or
you can use a normal file on whatever file system, or a real device, as
desired).
What might be tricky is anything that claims to return "space left",
depending exactly on what you want it to mean. But (I think) certain LVM
setups have similar issues.
Asking 'space left' for a volume directly isn't really applicable - that's
a
property of the file system on the volume instead. 'Space left' in a pool
is basically an indication of how much space is available for allocating
additional pools. Allowing you ask 'is that space to allocate a 10 GB
volume in this pool?' rather than just blindly trying & failing
Dan.
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