An update for the situation.<br><br>It seems that the lockup situation when we brought in the new server is not quite exactly the same behavior as before.<br><br>Running "iozone -O" on the new machine, which mount OCFS2 without serving the content yet (the load is very low), could leads to OCFS2 lockup for 60-90 seconds. This happened very frequently (running iozone 3 times and this happened once). On the other hand, I run "iozone -O 50" times on the older server without having this lockup. Sometime it slow (few seconds), but not this slow.<br>
<br>When the lockup occur, both machine would hang. Even simple ls just hang. The funny thing is that, sometime, iozone command is actually not yet running. It just start to spawn the command and lockup occurred, so strace show nothing suspicious. In case it hang in the middle of iozone, the system call the takes long time vary from sync, read, write, and lseek.<br>
<br>I tried simpler things like repeatedly do "ls" or just "echo hello world > test" but it didn't cause this problem. The command that will cause this lockup almost certainly is just "iozone -O" and it must be called on the second server.<br>
<br><br><div class="gmail_quote">2010/1/28 Somsak Sriprayoonsakul <span dir="ltr"><<a href="mailto:somsaks@gmail.com">somsaks@gmail.com</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
For our case log file shouldn't be the problem since it's store locally. But fragmentation might be the cause. We serve a lot of small files (mostly html and jpg) out of OCFS2. And the file come in and go out very frequently, old topic will be paged out to archive directory out of OCFS2, while new topic are created on OCFS2. Thanks for pointing the bug report then. <br>
<br>Right now we are using 4 slots and planning to serving about 4 in near future. I think we shouldn't decrease the number of slot right now. <br><br>Are there any other statistics that we should observe for? <br><br>
<div class="gmail_quote">2010/1/28 Brad Plant <span dir="ltr"><<a href="mailto:bplant@iinet.net.au" target="_blank">bplant@iinet.net.au</a>></span><br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div><div></div><div class="h5">
Hi Somsak,<br>
<br>
I observed high loads and apache slowness when there was insufficient contiguous free space due to fragmentation. I believe it was because apache couldn't write it's log files efficiently. We had 2 apache nodes and I found that stopping apache on the problem node resolved the problem until I deleted lots of unused files.<br>
<br>
My symptoms don't seem to suggest a slow open() syscall like your strace results are showing, but I certainly got the high load and poor apache performance. It might be worth checking out anyway. There is a bug report and we're just waiting for the patch to get reviewed and made publicly available.<br>
<br>
<a href="http://oss.oracle.com/bugzilla/show_bug.cgi?id=1189" target="_blank">http://oss.oracle.com/bugzilla/show_bug.cgi?id=1189</a><br>
<br>
Cheers,<br>
<font color="#888888"><br>
Brad<br>
</font><div><div></div><div><br>
<br>
<br>
On Tue, 19 Jan 2010 16:12:07 +0700<br>
Somsak Sriprayoonsakul <<a href="mailto:somsaks@gmail.com" target="_blank">somsaks@gmail.com</a>> wrote:<br>
<br>
> Hello,<br>
><br>
> We are using OCFS2 version 1.4.3 on CentOS5, x86_64 with 8GB memory. The<br>
> underlying storage is HP 2312fc smart array equipped with 12 SAS 15K rpm,<br>
> configured as RAID10 using 10 HDDs + 2 spares. The array has about 4GB<br>
> cache. Communication is 4Gbps FC, through HP StorageWorks 8/8 Base e-port<br>
> SAN Switch. Right now we only have this machine connect to the SAN through<br>
> switch, but we plan to add more machine to utilize this SAN system.<br>
><br>
> Our application is apache version 1.3.41, mostly serving static HTML file +<br>
> few PHP. Note that, we have to downgrade to 1.3.41 due to our application<br>
> requirement. Apache is configured on has 500 MaxClients.<br>
><br>
> The storage OCFS2 are formatted with mkfs.ocfs2 without any special option<br>
> on. It run directly from multipath'ed SAN storage without LVM or software<br>
> RAID. We mount OCFS2 with noatime, commit=15, and data=writeback (as well as<br>
> heartbeat=local). Our cluster.conf is like this<br>
><br>
> cluster:<br>
> node_count = 1<br>
> name = mycluster<br>
><br>
> node:<br>
> ip_port = 7777<br>
> ip_address = 203.123.123.123<br>
> number = 1<br>
> name = <a href="http://mycluster.mydomain.com" target="_blank">mycluster.mydomain.com</a><br>
> cluster = mycluster<br>
><br>
> (NOTE: Some details are neglected here, such as hostname and IP address).<br>
><br>
> Periodically, we found that the file system work very slow. I think that it<br>
> happened once every few minutes. When the file system slow, httpd process<br>
> CPU utilization will goes much higher to about 50% or above. I tried to<br>
> debug this slow by creating a small script that periodically do<br>
><br>
> strace -f dd if=/dev/zero of=/san/testfile bs=1k count=1<br>
><br>
> And time the speed of dd, usually dd will finish within subsecond, but<br>
> periodically dd will be much slower to about 30-60 seconds. Strace output<br>
> show this.<br>
><br>
> 0.000026 open("/san/testfile", O_WRONLY|O_CREAT|O_TRUNC, 0666) = 1<br>
> 76.418696 rt_sigaction(SIGUSR1, NULL, {SIG_DFL, [], 0}, 8) = 0<br>
><br>
> So I presume that this mean the open system call is periodically very slow.<br>
> I did about 5-10 tests which yield similar strace'd results (ranging from<br>
> just 5-7 seconds to 80 seconds).<br>
><br>
> So my question is, what could be the cause of this slowness? How could I<br>
> debug this deeper? On which point should we optimize the file system?<br>
><br>
> We are in the process of purchasing and adding more web servers to the<br>
> system and use reverse proxy to load balance between two servers. We just<br>
> want to make sure that this will not make situation worst.<br>
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