# [SOLVED] DM snapshot-merge: see when merge is completed?

## boerKrelis

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?

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## boerKrelis

Got it working with lvm2-2.02.60 . 

```
dmsetup status your-snapshotmerge-dm-device
```

 will show 

<sectors_allocated>/<total_sectors> <metadata_sectors>

So merging has finished when <sectors_allocated> == <metadata_sectors>

See this message on the dm-devel@redhat.com mailing list.

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