Wiesner Thomas wrote:
Before running Linux software raid on a production system, I'm trying
to get the hang of it and use
4 loopback devices on which I play with RAID5.
I've:
* mdadm - v2.6.3 - 20th August 2007
* mke2fs 1.37 (21-Mar-2005) Using EXT2FS Library version 1.37
* Linux hazard 2.6.22.5 #2 PREEMPT Wed Aug 29 13:06:26 CEST 2007
i686 GNU/Linux
The HDD can transfer appriximately 40MB/s and the loopback files are
only 200 to 350MB.
Well when I create a MD with
mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3
/dev/loop0 /dev/loop1 /dev/loop2
and try to create the filesystem on it with
mke2fs /dev/md0
mke2fs gets stuck in D state. Not always but sometimes. It hangs there
for different amounts of time, at least a
Minute or two. (Far longer than the filesystem creation process itself
takes.) Afterwards, the process continues and finishes.
Sometimes it hangs at 6/65 blocks, sometimes earlier, sometimes later,
but always quite early.
The interesting line of a "ps ax" looks like:
1609 tty2 D+ 0:00 mke2fs -j /dev/md0
It doesn't seem to be a real showstopper, but I think it's not a
normal behaviour.
While stuck, I don't see any CPU or disk activity. Trying to kill the
mke2fs seems to lead to
a completely stuck mke2fs (doesn't get out of D state) but I don't
know that for sure, because I did
that only once and didn't wait very long before I rebooted.
The base System is a 3.1 (Sarge) with a plain Vanilla 2.6.22.5 kernel
and latest mdadm.
If you need additional info or I should try something, I'm willing to
do that, because I've some time ATM.
Has there been any progress on this? I think I saw it, or something
similar, during some testing of recent 2.6.23-rc kernels, on mke2fs took
about 11 min longer than all the others (~2 min) and it was not
repeatable. I worry that process of more interest will have the same hang.
--
bill davidsen <[EMAIL PROTECTED]>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979
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