Hi all,
I'm getting back to this now that I'll have time, apologies for the
delay. So, is the following correct in the case of a read error?
1) System tries to read an unreadable sector
2) Drive timeout reports unreadable based on drive timeout setting.
2a) In this case, mdadm sees the sector is unreadable and rewrites it
elsewhere on that drive.
3) If linux hangcheck timer runs out before the drive timeout, then
linux aborts the read, logs an error, and mdadm isn't given a chance to
rewrite elsewhere based on checksums.
I'm not sure how the linux io timeout fits in here, and how it's
different from the hangcheck timer.
Given all this, it seems to me that I should now set the hangcheck timer
to something greater than drive timeout (180 seconds). Does that sound
right? Otherwise, linux will kill the rewrite again, no?
Thanks,
Allie
On 10/12/2017 4:52 PM, Edward Kuns wrote:
On Thu, Oct 12, 2017 at 10:16 AM, Edward Kuns <eddie.kuns@xxxxxxxxx> wrote:
All y'all referring to a whole separate kernel module, hangcheck-timer.ko?
Looking back at the original messages:
[4038193.380403] INFO: task md2_raid5:247 blocked for more than 120 seconds.
[4038193.380473] Not tainted 4.4.0-81-generic #104~14.04.1-Ubuntu
[4038193.380526] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
disables this message.
it looks like you're dealing with this part of the kernel:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/hung_task.c
The timer is configurable with sysctl and defaults to 120 seconds.
You can check with this command:
$ sudo sysctl kernel.hung_task_timeout_secs
kernel.hung_task_timeout_secs = 120
You can adjust it temporarily (e.g. to make it longer):
$ sudo sysctl -w kernel.hung_task_timeout_secs=150
Or you can adjust it permanently by modifying your sysctl configuration.
It looks like by default it will only warn ten times. After that it
will stop complaining. That is also configurable via sysctl.
Eddie
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