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| author | Mike Snitzer <snitzer@redhat.com> | 2010-03-06 02:29:56 +0000 |
|---|---|---|
| committer | Alasdair G Kergon <agk@redhat.com> | 2010-03-06 02:29:56 +0000 |
| commit | c53a381efbe3d0e0629121b3f0d2b62a0e167791 (patch) | |
| tree | 96807004e3f27c7030e744b95f0b1e2d73223e8d | |
| parent | ecdb2e257abc33ae6798d3ccba87bdafa40ef6b6 (diff) | |
dm: document when snapshot has finished merging
Update Documentation/device-mapper/snapshot.txt to cover "How to
determine when a snapshot has finished merging".
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
| -rw-r--r-- | Documentation/device-mapper/snapshot.txt | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/Documentation/device-mapper/snapshot.txt b/Documentation/device-mapper/snapshot.txt index e3a77b21513..0d5bc46dc16 100644 --- a/Documentation/device-mapper/snapshot.txt +++ b/Documentation/device-mapper/snapshot.txt @@ -122,3 +122,47 @@ volumeGroup-base: 0 2097152 snapshot-merge 254:11 254:12 P 16 brw------- 1 root root 254, 11 29 ago 18:15 /dev/mapper/volumeGroup-base-real brw------- 1 root root 254, 12 29 ago 18:16 /dev/mapper/volumeGroup-base-cow brw------- 1 root root 254, 10 29 ago 18:16 /dev/mapper/volumeGroup-base + + +How to determine when a merging is complete +=========================================== +The snapshot-merge and snapshot status lines end with: + <sectors_allocated>/<total_sectors> <metadata_sectors> + +Both <sectors_allocated> and <total_sectors> include both data and metadata. +During merging, the number of sectors allocated gets smaller and +smaller. Merging has finished when the number of sectors holding data +is zero, in other words <sectors_allocated> == <metadata_sectors>. + +Here is a practical example (using a hybrid of lvm and dmsetup commands): + +# lvs + LV VG Attr LSize Origin Snap% Move Log Copy% Convert + base volumeGroup owi-a- 4.00g + snap volumeGroup swi-a- 1.00g base 18.97 + +# dmsetup status volumeGroup-snap +0 8388608 snapshot 397896/2097152 1560 + ^^^^ metadata sectors + +# lvconvert --merge -b volumeGroup/snap + Merging of volume snap started. + +# lvs volumeGroup/snap + LV VG Attr LSize Origin Snap% Move Log Copy% Convert + base volumeGroup Owi-a- 4.00g 17.23 + +# dmsetup status volumeGroup-base +0 8388608 snapshot-merge 281688/2097152 1104 + +# dmsetup status volumeGroup-base +0 8388608 snapshot-merge 180480/2097152 712 + +# dmsetup status volumeGroup-base +0 8388608 snapshot-merge 16/2097152 16 + +Merging has finished. + +# lvs + LV VG Attr LSize Origin Snap% Move Log Copy% Convert + base volumeGroup owi-a- 4.00g |