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Re: [libvirt] [RFC] Add flag for virsh undefine to remove/wipe the disk devices



于 2011年03月30日 21:50, Daniel Veillard 写道:
On Wed, Mar 30, 2011 at 09:39:14PM +0800, Osier Yang wrote:
Hi, All

I'm thinking to introduce a new flag (something like --remove-disks,
--wipe-disks) for "virsh undefine", so that the user can choose
whether to remove/wipe the disk devices or not, have seen this
requirement in many places, @libvirt-users, public #virt, and also
we have a bug of this function. So, IMHO this is a reasonable
requirement, following is the rough thoughts:

1) General idea.
    As we don't have a API which can get all the disk devices of a
    domain, perhaps need to write functions to parse domain xml to
    extract the disks' path (this is annoyed, but seems don't other
    way), and then lookup them by storage volume API
    (virStorageVolLookupByPath), and then can remove or wipe
    the volume by (virStorageVolDelete/virStorageVolWipe).

    And for the disk path which doesn't belong to any storage pool,
    simply remove it by "unlink()"?

   Won't work for connection to remote hosts.

Hmm, yes, :-)


2) Which type of devices can not be removed/wiped.

    * Can't delete/wipe ISCSI/SCSI vol.
    * Vol doesn't exists (which will throw an warning when do
      virStorageVolLookupByPath).
    * Have no write permission on the parent directory of the
      disk path.
    * Can't delete/wipe the disk device which is passthrough'ed
      from host, (e.g. /dev/sr0 as a CDROM device for guest)
    * The storage pool which the disk device belongs to as a vol
      is marked as "share"
    * The storage pool which the disk device belongs as a vol is
      readonly
    * can't delete disk device of network type.
    * Any others?

    For these situations, we need to do checking and throw
    straightforward warnings to tell user why it can't be
    removed/wiped.

   I would rather make this a flag of virDomainUndefine(), except
there is no flag argument for it :(

Yes, actually I also prefer to add new flag to API, but not in
virsh instead, however, adding new flag argument is not workable,
how about introduce a new API, something like "virDomainUndefineFlag"?


   I think if we want this to work well tis should be based on
API operations only,

Daniel



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