root: Failed query for merging percentage. Aborting merge

[Roger Morton <ttguy1@gmail.com>]

Thanks for the reply Zdenek,

So just to make sure I have this correct - you think that my merge was probably working just fine and that all I needed was patience. 

I just needed to wait until the merge completed?

An answer on http://serverfault.com/questions/559649/see-progress-of-lvm-merge tells me that

" lvs -a: Data% columns will go down to 0% while merging  "

So here is my  lvs -a - Data% is nothing on root now. So I guess that means it has completed.

god@new-desktop:~$ sudo lvs -a
 LV                 VG         Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
 home_lv            kubuntu-vg rwi-aor--- 1000.00g                                    100.00           
 root               kubuntu-vg owi-aor---   50.00g                                    100.00 

And in fact today I can create a new snapshot of root. So the merge has completed - I guess.

So really what was that error that told me "Aborting merge" ?  You are telling me that it did not abort the merge. It was just doing it in the back ground?  I would humbly suggest that this message be changed!!  Because "Aborting merge" sure sounds like the system is giving up on doing the merge.  Which causes concerns to the joe shmo user like me.   

On Mon, Apr 10, 2017 at 8:54 PM, Zdenek Kabelac <zkabelac@redhat.com> wrote:

Dne 9.4.2017 v 09:17 Roger Morton napsal(a):

I wanted to merge a old snap shot (root_snap10) of my root file system back
into root.


    LV          VG         Attr       LSize    Pool Origin Data%  Meta%  Move
Log Cpy%Sync Convert
  home_lv     kubuntu-vg rwi-aor--- 1000.00g
 100.00
  root        kubuntu-vg owi-aor---   50.00g
 100.00
  root_snap10 kubuntu-vg swi-a-s---   50.00g      root   28.42
  root_snap14 kubuntu-vg swi-a-s---   50.00g      root   0.00

In genernal -


Once the merge IS started -  you see immediately 'the merged state' and  the
blocks are moved in background (they are moved back from COW to origin -
while you already see a device in 'merged-state').

While the merge IS happening you can't merge another LV.

So you need to wait till merge of snap10 is finished (0%).

sudo lvcreate -s -n root_snap10b -L 50G /dev/kubuntu-vg/root
  Snapshots of an origin that has a merging snapshot is not supported

So the system still thinks   /dev/kubuntu-vg/root is in the middle of merging.
Which worries me - my root file system might be in some half and half state
between two different snapshots

As said there is never 'half and half state' - this would clearly never work ;) you can't see  old & new data mixed at the same time.


Regards


Zdenek

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