From mboxrd@z Thu Jan  1 00:00:00 1970
References: <CAHEKYV7Uvqm2knzb4QsTxtdec2Wi+mnFi2Q6MbP95gseS5V7Ow@mail.gmail.com>
From: Zdenek Kabelac <zkabelac@redhat.com>
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Date: Wed, 22 Jan 2020 14:12:37 +0100
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Subject: Re: [linux-lvm] Failed merge, still running?
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To: LVM general discussion and development <linux-lvm@redhat.com>, Mauricio Tavares <raubvogel@gmail.com>

Dne 22. 01. 20 v 11:58 Mauricio Tavares napsal(a):
> So after a botched package update I decided to revert to the snapshot
> I took just before doing the update. After shutting guest down, I
> started
> 
> lvconvert --merge vmhost_vg0/desktop_snap_20200121
> 
> and instead of seeing the usual percentage of how far it has
> completed, I got nothing. lvs -a -o +devices shows
> 
>    LV                      VG         Attr       LSize  Pool Origin
> Data%  Meta%  Move Log Cpy%Sync Convert Devices
>    desktop                 vmhost_vg0 Owi-a-s--- 20.00g
>                                       /dev/sdb3(14848)
>    [desktop_snap_20200121] vmhost_vg0 Swi-a-s--- 10.00g      desktop 100.00
> 
> I see nothing when I do lsof against both the lv (lsof
> /dev/vmhost_vg0/desktop) and its snapshot. dmsetup tells me:
> 
> [root@vmhost ~]# dmsetup info /dev/vmhost_vg0/desktop
> Name:              vmhost_vg0-desktop
> State:             ACTIVE
> Read Ahead:        256
> Tables present:    LIVE
> Open count:        0
> Event number:      0
> Major, minor:      253, 5
> Number of targets: 1
> UUID: LVM-qa4WnlE7w8V7pasHwdNH6bnpz2ajYY1F2ZXwTWzpUE2r6eE2DftMGLHdeATE8XAq
> 
> [root@vmhost ~]# dmsetup info /dev/vmhost_vg0/desktop_snap_20200121
> Name:              vmhost_vg0-desktop_snap_20200121
> State:             ACTIVE
> Read Ahead:        256
> Tables present:    LIVE
> Open count:        0
> Event number:      0
> Major, minor:      253, 15
> Number of targets: 1
> UUID: LVM-qa4WnlE7w8V7pasHwdNH6bnpz2ajYY1FkyXcvv8ai1Sc0q5zlsXeenYOqCPUXs3M
> 
> [root@vmhost ~]#
> 
> Before I blow that lv up, what else should I be checking?


Hi


Merging can ONLY start when devices are not in-use - so if you've issued merge 
command while devices were still opened - the 'merge' operation has
been just committed into lvm2 metadata and the actual merge would normally 
happen/start with next activation of the merged LV.

You can invoke it also by issuing 'lvchange --refresh' which may start to 
merging (if the conditions do allow the operation to start).

Regard

Zdenek