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| author | Kevin Wolf <kwolf@redhat.com> | 2012-04-12 13:20:41 +0200 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2012-04-20 15:57:27 +0200 |
| commit | 4fabffc11234d0587a213418574095e036110cd2 (patch) | |
| tree | 2fdfd1e834a37627e59d3eeeccbf5f38bfdd1e36 /block/qcow2.h | |
| parent | f24423bd902bce29bc546cf8d030bfa369726ab1 (diff) | |
| download | qemu-4fabffc11234d0587a213418574095e036110cd2.zip qemu-4fabffc11234d0587a213418574095e036110cd2.tar.gz qemu-4fabffc11234d0587a213418574095e036110cd2.tar.bz2 | |
Specification for qcow2 version 3
This updates the qcow2 specification to cover version 3. It contains the
following changes:
- Added compatible/incompatible/auto-clear feature bits plus an optional
feature name table to allow useful error messages even if an older
version doesn't know some feature at all.
- Configurable refcount width. If you don't want to use internal
snapshots, make refcounts one bit and save cache space and I/O.
- Zero cluster flags. This allows discard even with a backing file that
doesn't contain zeros. It is also useful for copy-on-read/image
streaming, as you'll want to keep sparseness without accessing the
remote image for an unallocated cluster all the time.
- Fixed internal snapshot metadata to use 64 bit VM state size. You
can't save a snapshot of a VM with >= 4 GB RAM today.
- Extended internal snapshot metadata to contain the disk size, so that
resizing images that have snapshots can be allowed in the future.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'block/qcow2.h')
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