On Sun, Jan 24 2010 at 9:12am -0500, Wicher Minnaard <wicher@xxxxxxxxxx> wrote: > Hi, I'm new to the list. > I'm experimenting with the snapshot-merge target on a 2.6.33_rc4 kernel: > > echo 0 $(blockdev --getsize /dev/mapper/original) snapshot-merge > /dev/mapper/original /dev/loop1 p 8 | dmsetup create mergeomatic > > where /dev/loop1 is a COW volume I created earlier (with the > 'snapshot' target, against /dev/mapper/original, of course). > I wait for some time and then I just 'dmsetup remove' to break down > the device stack, starting with the 'mergeomatic' device. I then take > a look at /dev/mapper/original, and, much to my delight, I see stuff > that has been merged back in from the snapshot. > > But I don't know how to determine whether the merge has completed. I > looked around in /proc and /sys, but those contained no obvious clues > (not obvious to me, that is). My kernel logs never mention any dm > activity (whereas the md driver is quite chatty and features > /proc/mdstat). > Any suggestions greatly appreciated. Hi Wicher, The status for the snapshot-merge (and snapshot) target was extended to include the "allocated metadata sectors" at the end of its status output, see commit: http://git.kernel.org/linus/985903bb3a6d98 And here is the corresponding lvm2 commit: http://sources.redhat.com/git/?p=lvm2.git;a=commit;h=f02531802c002 The format is: <sectors_allocated>/<total_sectors> <metadata_sectors> So merging has finished when <sectors_allocated> == <metadata_sectors> Here is a practical example (using 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 Merge has completed # 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
