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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.

dme.


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