[linux-lvm] LVM RAID1 syncing component

[Joe Lawrence]

On Tue, 25 Nov 2014 22:42:38 -0700

Does anyone know how its possible to determine which side of an LVM RAID 1
is the stale partner during RAID resync?
In ordinary MD RAID, I believe you can check
/sys/block/md0/md/dev-XXX/state, but LVM RAID seems to hide those files
when leveraging the MD code. I've looked though pvs/vgs/lvs manpages, but
can't figure anything out there either.

Rather indirectly: iotop which will show you which devices are mostly
being read from and written to.
# lvs -a -o copy_percent
Anything less than 100% is syncing. I think.

* lvs, lv_attr bit Volume Health: (p)artial
* vgs, vg_attr bit (p)artial: one or more physical volumes belonging
to the volume group are missing from the system
* pvs, pv_attr bit (m)issing

along with the lvs copy_percent (is this similar to sync_percent) that
you mentioned. That's about it.

Since there seems to be no real underlying MD device, I'm assuming that
ioctls are out of the question as well.

-- Joe

[Heinz Mauelshagen]

With DM/LVM it is always the last images added when converting (to)
raid1; see "lvs -a".

If you for instance convert from linear to raid1 with "lvconvert -m1
--type raid1 $LV",
the second (and last) device named /dev/$VG/${LV}_rimage_1 will be
resynchronized
from the first /dev/$VG/${LV}_rimage_0 (i.e. the former linear device).

As mentioned below, the copy_percent aka sync_percent tells you how far
the sync process got
unless 100% when it's finished.

-- lvmguy

Post by Joe Lawrence
On Tue, 25 Nov 2014 22:42:38 -0700

Does anyone know how its possible to determine which side of an LVM RAID 1
is the stale partner during RAID resync?
In ordinary MD RAID, I believe you can check
/sys/block/md0/md/dev-XXX/state, but LVM RAID seems to hide those files
when leveraging the MD code. I've looked though pvs/vgs/lvs manpages, but
can't figure anything out there either.

Rather indirectly: iotop which will show you which devices are mostly
being read from and written to.
# lvs -a -o copy_percent
Anything less than 100% is syncing. I think.

* lvs, lv_attr bit Volume Health: (p)artial
* vgs, vg_attr bit (p)artial: one or more physical volumes belonging
to the volume group are missing from the system
* pvs, pv_attr bit (m)issing
along with the lvs copy_percent (is this similar to sync_percent) that
you mentioned. That's about it.
Since there seems to be no real underlying MD device, I'm assuming that
ioctls are out of the question as well.
-- Joe
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