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authorPavel Butsykin <pbutsykin@virtuozzo.com>2016-07-22 11:17:52 +0300
committerKevin Wolf <kwolf@redhat.com>2016-09-05 19:06:48 +0200
commit13b9414b5798539e2dbb87a570d96184fe21edf4 (patch)
treeb78f6ea0b47ef741ec29787c15fe57edf2b98dcc /hmp-commands.hx
parentdc7a4a9ed170c19b4036cef2720d3e8fb551cc0f (diff)
downloadqemu-arm-13b9414b5798539e2dbb87a570d96184fe21edf4.tar.gz
drive-backup: added support for data compression
The idea is simple - backup is "written-once" data. It is written block by block and it is large enough. It would be nice to save storage space and compress it. The patch adds a flag to the qmp/hmp drive-backup command which enables block compression. Compression should be implemented in the format driver to enable this feature. There are some limitations of the format driver to allow compressed writes. We can write data only once. Though for backup this is perfectly fine. These limitations are maintained by the driver and the error will be reported if we are doing something wrong. Signed-off-by: Pavel Butsykin <pbutsykin@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Denis V. Lunev <den@openvz.org> CC: Jeff Cody <jcody@redhat.com> CC: Markus Armbruster <armbru@redhat.com> CC: Eric Blake <eblake@redhat.com> CC: John Snow <jsnow@redhat.com> CC: Stefan Hajnoczi <stefanha@redhat.com> CC: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'hmp-commands.hx')
-rw-r--r--hmp-commands.hx8
1 files changed, 5 insertions, 3 deletions
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 848efee5d1..74f32e515c 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1182,8 +1182,8 @@ ETEXI
{
.name = "drive_backup",
- .args_type = "reuse:-n,full:-f,device:B,target:s,format:s?",
- .params = "[-n] [-f] device target [format]",
+ .args_type = "reuse:-n,full:-f,compress:-c,device:B,target:s,format:s?",
+ .params = "[-n] [-f] [-c] device target [format]",
.help = "initiates a point-in-time\n\t\t\t"
"copy for a device. The device's contents are\n\t\t\t"
"copied to the new image file, excluding data that\n\t\t\t"
@@ -1191,7 +1191,9 @@ ETEXI
"The -n flag requests QEMU to reuse the image found\n\t\t\t"
"in new-image-file, instead of recreating it from scratch.\n\t\t\t"
"The -f flag requests QEMU to copy the whole disk,\n\t\t\t"
- "so that the result does not need a backing file.\n\t\t\t",
+ "so that the result does not need a backing file.\n\t\t\t"
+ "The -c flag requests QEMU to compress backup data\n\t\t\t"
+ "(if the target format supports it).\n\t\t\t",
.mhandler.cmd = hmp_drive_backup,
},
STEXI