doc: Document that snapshot name of block-backed disk isn't autogenerated

Libvirt generates external snapshot target file names for file backed
storage but not for block backed storage. Document the limitation.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1032363
This commit is contained in:
Peter Krempa 2014-07-11 10:20:33 +02:00
parent 270969c4dd
commit 500f80a595
2 changed files with 8 additions and 4 deletions

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@ -164,9 +164,11 @@
attribute <code>type</code> giving the driver type (such attribute <code>type</code> giving the driver type (such
as qcow2), of the new file created by the external as qcow2), of the new file created by the external
snapshot of the new file. If <code>source</code> is not snapshot of the new file. If <code>source</code> is not
given, a file name is generated that consists of the given and the disk is backed by a local image file (not
existing file name with anything after the trailing dot a block device or remote storage), a file name is
replaced by the snapshot name. Remember that with external generated that consists of the existing file name
with anything after the trailing dot replaced by the
snapshot name. Remember that with external
snapshots, the original file name becomes the read-only snapshots, the original file name becomes the read-only
snapshot, and the new file name contains the read-write snapshot, and the new file name contains the read-write
delta of all disk changes since the snapshot. delta of all disk changes since the snapshot.

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@ -3219,7 +3219,9 @@ The I<--diskspec> option can be used to control how I<--disk-only> and
external checkpoints create external files. This option can occur external checkpoints create external files. This option can occur
multiple times, according to the number of <disk> elements in the domain multiple times, according to the number of <disk> elements in the domain
xml. Each <diskspec> is in the xml. Each <diskspec> is in the
form B<disk[,snapshot=type][,driver=type][,file=name]>. To include a form B<disk[,snapshot=type][,driver=type][,file=name]>. A I<diskspec>
must be provided for disks backed by block devices as libvirt doesn't
auto-generate file names for those. To include a
literal comma in B<disk> or in B<file=name>, escape it with a second literal comma in B<disk> or in B<file=name>, escape it with a second
comma. A literal I<--diskspec> must precede each B<diskspec> unless comma. A literal I<--diskspec> must precede each B<diskspec> unless
all three of I<domain>, I<name>, and I<description> are also present. all three of I<domain>, I<name>, and I<description> are also present.