[linux-lvm] lvcreate hangs forever and udev work timeout

Eric Ren renzhengeek at gmail.com
Sun Apr 14 07:30:19 UTC 2019


The reason is found out, as you've predicted.

> is it because of slow read operation (i.e. some raid arrays are known to
> wake-up slowly)

The udev worker is blocked until timeout before killed, cause the
"blkid" in /usr/lib/udev/rules.d/13-dm-disk.rules is too slow because
of high IO load on the thin pool.

After remove this rule:


for testing, the problem cannot be reproduced any more.

But, we tried to increate udevd timeout to 5 min, the problem still
happens; with 10 min timeout, can workaround this problem.

>From my understanding, the blkid will only read the fs superblock, why
it takes so long for a small IO to finish, even under high IO load?


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