Re: parted/LVM for ET [Re: [Libvir] Storage manager initial requirements and thoughts

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.