System hang due to high iowait
Wayne Pinette
Wpinette at cariboo.bc.ca
Thu Oct 7 15:24:53 UTC 2004
Hmmm Im not sure. All of my drives are ext3 drives (including the one
with that patch I sent).
I know the server which I had to do it on isn't handling large data
files, but rather many many many
small ones (mail server with anti-virus scan which handles ~1800
messages an hour so it's all disk io).
Im still guessing you want to mess with the pagecache settings.
Perhaps try a larger number.
(2 10 75 /proc/sys/vm/pagecache) .
Wayner
>>> csu4 at fedex.com 06/10/2004 11:32:52 pm >>>
Hi Wayne,
Thanks a lot for the tips. I did have a try:
1. If the file system is ext2 for the large IO operation,
then your work around works;
2. If the file system is ext3, then it hangs again.
I'm wondering if this is ext3 problem or the parameter you
mentioned must be adjusted for ext3?
Thx & Rgds,
schyu
Wayne Pinette
<Wpinette at cariboo.bc To:
redhat-list at redhat.com
.ca> cc:
Sent by: Subject: Re: System
hang due to high iowait
redhat-list-bounces@
redhat.com
2004-10-04 23:19
Please respond to
General Red Hat
Linux discussion
list
I had a similar problem and did a google search on it a while back. I
found this little snippet and
tried it and have never had a problem since :
In your rc.d/rc.local file append the following two lines :
echo 100 > /proc/sys/vm/inactive_clean_percent
echo 2 10 20 > /proc/sys/vm/pagecache
I would give this a try.
Wayner
>>> csu4 at fedex.com 04/10/2004 1:46:04 am >>>
Hi there,
Could anyone help to find the system hung problem? The box
is running RHEL 3AS Update3. Whenever I do a massive data
transfer (such as rcp from another box to this box), after
certain time (around six to seven hours), this box would
hang up. I could see the top output even it's hung, and it
showed that the iowait is 99% and system contributed another
1% making the server moving nowhere.
The box connected to a HP MSA500 Smart Array Storage, thru
multipath (I enabled it following the user guide) connection.
The filesystem is ext3 format. Any problem here?
Thx & Rgds,
SCHYU
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