[linux-lvm] Mounted, but idle LVM volume causes constant disk writes

[Bostjan Skufca]

Hello,

If LVM2 volume is mounted (ext4 fs), why is there constant write activity
to the devices below (sw raid in this case) despite not using the mounted
volume at all?

I am seing this on multiple hosts. On this particular one I am seeing
around 20 writes per second on average, but they occur in batches of around
50-90 writeIOps on every 3-4 seconds. If I mount the same filesystem (ext4)
on sw raid1 without LVM in between, I see the expected 0 write IOps when
not using the filesystem.

Kernel versions where I noticed this: 3.0.13 (sysrescd) 3.4.1, 3.9.4
(custom compiled). I noticed it on all systems where lvm is in use.

Thank you for the hints,
b.


PS: I did search the web first, but I could not find the answer. Sorry if
this has been answered before, maybe I was searching for the wrong terms.
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