On Tue, Mar 20, 2007 at 02:32:10PM +0000, Daniel P. Berrange wrote:
> - There are a couple of different types of storage pool
> - An LVM volume group
> - Block devices
> - A directory on a filesystem
> - Each storage pool can have zero or more storage volumes allocated
> - LVM volume group has multiple logical volumes
> - Block device has multiple partitions
> - A directory has multiple files (maybe sparse)
> - Each storage pool has some measure of free space
> - LVM volume group has unallocated physical extents
> - Block device has unpartitioned sectors
> - A directory has free space from underlying filesystem
> - Every host has at least one storage pool with free space - ie a directory
> on a filesystem. Some hosts may also have free LVM space, or unpartitioned
> block devices but we can't assume their presence in general.
ZFS takes a slightly different view:
- ZFS storage pools are collections of physical devices (including
data replication),
- ZFS datasets are contained within ZFS storage pools and are
either filesystems, volumes or snapshots.
- ZFS filesystems are, well, filesystems,
- ZFS volumes are available as block devices,
- ZFS volumes can contain multiple partitions.
Currently we anticipate using both file-based images (inside ZFS and
other filesystems) and ZFS volumes (to provide the impression of a
dedicated physical device) for VMs, as well as dedicating real
physical volumes, obviously.
Overall this fits with your model, I think.
dme.