-------- Original Message --------
Subject: Re: possible bus loading problem during resync
Date: Wed, 10 Mar 2010 23:23:23 -0700
From: Timothy D. Lenz <tlenz@xxxxxxxxxx>
To: Goswin von Brederlow <goswin-v-b@xxxxxx>
On 3/10/2010 10:53 PM, Goswin von Brederlow wrote:
Asdo<asdo@xxxxxxxxxxxxx> writes:
Kristleifur Daðason wrote:
On Tue, Mar 9, 2010 at 6:31 AM, Timothy D. Lenz<tlenz@xxxxxxxxxx> wrote:
I'm working on 2 systems that are mainly for running vdr. I've had these
running somewhat for awhile with raid. But a couple nights ago as I was
quitting for the night, I noticed one of the computers drive light staying
on. I had just made some changes to xine and didn't know if something had
crashed. Turned on the TV and found the video was freezing for 10-20secs
every 10-20secs. Logging in using putty and winscp I found it very sluggish
to respond.Starting top I found it was doing the regular array check/resync.......
--
Sorry about the incredibly brief answer: Not to dismiss other issues,
but that behavior seems like exactly what I've seen when a disk has
been failing.
If that is true, how does that happen, the driver is hung? But anyway,
how can such things happen when there is more than one CPU-core?
A drive produces an error, the whole controler hangs and resets all
ports, all drives have to finish being reset before any IO can continue.
Hapens easily enough.
try disabling NCQ by echo 1> /sys/block/sdX/device/queue_depth for
all drives. After doing this, at most 1 request can be issued to one
drive until the drive has serviced such request.
After doing this, firstly I'd say the sluggishness should disappear,
at least on SSH when not touching the disks. And then you can look
with "iostat -x 1": probably the bad drive will have a service time
(svctm) or await much worse than the others.
Just guesses, correct me if I'm wrong
What I would start with is check the resync/check speed of the raid and
kernel messages. If it is running at high speed and there are no kernel
messages about IO errors then it is probably just a case of the IO
subsystem being busy. I got similar sluggish behaviour when I increased
the stripe cache to 16384 for a reshape.
If there are no hardware problems on the disks causing this then try
setting the max speed for the resync lower. That way the resync will
leave pauses where other IO and bus activity can happen. The raid should
slow down automatically if there is normal IO pending but in my
experience that doesn't always work.
MfG
Goswin
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Found these 3 entries in /var/log/kern.log.1:
Mar 7 00:57:01 LLLx64-32 kernel: md: data-check of RAID array md0
Mar 7 00:57:01 LLLx64-32 kernel: md: minimum _guaranteed_ speed: 1000
KB/sec/disk.
Mar 7 00:57:01 LLLx64-32 kernel: md: using maximum available idle IO
bandwidth (but not more than 200000 KB/sec) for data-check.
Mar 7 00:57:01 LLLx64-32 kernel: md: using 128k window, over a total of
24418688 blocks.
Mar 7 00:57:01 LLLx64-32 kernel: md: delaying data-check of md1 until
md0 has finished (they share one or more physical units)
Mar 7 00:57:01 LLLx64-32 kernel: md: delaying data-check of md2 until
md1 has finished (they share one or more physical units)
Mar 7 00:57:01 LLLx64-32 kernel: md: delaying data-check of md1 until
md0 has finished (they share one or more physical units)
---------------------------------------------------------------------
Mar 7 01:02:50 LLLx64-32 kernel: md: md0: data-check done.
Mar 7 01:02:50 LLLx64-32 kernel: md: delaying data-check of md2 until
md1 has finished (they share one or more physical units)
Mar 7 01:02:50 LLLx64-32 kernel: md: data-check of RAID array md1
Mar 7 01:02:50 LLLx64-32 kernel: md: minimum _guaranteed_ speed: 1000
KB/sec/disk.
Mar 7 01:02:50 LLLx64-32 kernel: md: using maximum available idle IO
bandwidth (but not more than 200000 KB/sec) for data-check.
Mar 7 01:02:50 LLLx64-32 kernel: md: using 128k window, over a total of
4891712 blocks.
Mar 7 01:03:50 LLLx64-32 kernel: md: md1: data-check done.
Mar 7 01:03:50 LLLx64-32 kernel: md: data-check of RAID array md2
Mar 7 01:03:50 LLLx64-32 kernel: md: minimum _guaranteed_ speed: 1000
KB/sec/disk.
Mar 7 01:03:50 LLLx64-32 kernel: md: using maximum available idle IO
bandwidth (but not more than 200000 KB/sec) for data-check.
Mar 7 01:03:50 LLLx64-32 kernel: md: using 128k window, over a total of
459073344 blocks.
---------------------------------------------------------------------
Mar 7 02:47:43 LLLx64-32 kernel: md: md2: data-check done.
kern.log.1 ended at Mar 7 06:25:03
There was no ref to "raid" or "md" in /var/log/kern.log
I don't see any raid logs
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