Update Documentation/device-mapper/snapshot.txt to cover "How to determine when a snapshot has finished merging". Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx> --- Documentation/device-mapper/snapshot.txt | 42 ++++++++++++++++++++++++++++++ 1 files changed, 42 insertions(+), 0 deletions(-) diff --git a/Documentation/device-mapper/snapshot.txt b/Documentation/device-mapper/snapshot.txt index e3a77b2..7028a2a 100644 --- a/Documentation/device-mapper/snapshot.txt +++ b/Documentation/device-mapper/snapshot.txt @@ -122,3 +122,45 @@ 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 snapshot has finished merging +===================================================== +The status for the snapshot-merge (and snapshot) target includes the +"allocated metadata sectors". The snapshot(-merge) status format is: +<sectors_allocated>/<total_sectors> <metadata_sectors> + +Merging has finished when <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 + testlv1 test owi-a- 4.00g + testlv1_snap test swi-a- 1.00g testlv1 18.97 + +# dmsetup status test-testlv1_snap +0 8388608 snapshot 397896/2097152 1560 + ^^^^ metadata sectors + +# lvconvert --merge -b test/testlv1_snap + Merging of volume testlv1_snap started. + +# lvs test/testlv1 + LV VG Attr LSize Origin Snap% Move Log Copy% Convert + testlv1 test Owi-a- 4.00g 17.23 + +# dmsetup status test-testlv1 +0 8388608 snapshot-merge 281688/2097152 1104 + +# dmsetup status test-testlv1 +0 8388608 snapshot-merge 180480/2097152 712 + +# dmsetup status test-testlv1 +0 8388608 snapshot-merge 16/2097152 16 + +Merging has finished + +# lvs + LV VG Attr LSize Origin Snap% Move Log Copy% Convert + testlv1 test owi-a- 4.00g -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
