[CentOS] 3Ware 9550SX and latency/system responsiveness
feizhou at graffiti.net
Sun Sep 23 23:46:02 UTC 2007
Simon Banton wrote:
>>> At 17:34 +0800 14/9/07, Feizhou wrote:
>>>> .oh....do you have a BBU for your write cache on your 3ware board?
>>> Not installed, but the machine's on a UPS.
>> Ugh. The 3ware code will not give OK then until the stuff has hit disk.
> Having now installed BBUs, it's made no difference to the underlying
> responsiveness problem I'm afraid.
So a 3ware card will give OK once the stuff is in the cache and you have
selected write-cache enable even if there is no BBU? My apologies. My
previous experience has been with the 75xx and 85xx series which do not
have ram caches.
> With ports 2 and 3 now configured as RAID 0, with ext3 filesystem and
> mounted on /mnt/raidtest, running this bonnie++ command:
> bonnie++ -m RA-256_NR-8192 -n 0 -u 0 -r 4096 -s 20480 -f -b -d
> (RA- and NR- relate to kernel params for readahead and nr_requests
> respectively - the values above are Centos post-installation defaults)
> ...causes load to climb:
> 16:36:12 up 13 min, 2 users, load average: 8.77, 4.78, 1.98
> ... and uninterruptible processes:
> ps ax | grep D
> PID TTY STAT TIME COMMAND
> 59 ? D 0:03 [kswapd0]
> 2159 ? D 0:01 [kjournald]
> 2923 ? Ds 0:00 syslogd -m 0
> 4155 ? D 0:00 [pdflush]
> 4175 ? D 0:00 [pdflush]
> 4192 ? D 0:00 [pdflush]
> 4193 ? D 0:00 [pdflush]
> 4197 ? D 0:00 [pdflush]
> 4199 ? D 0:00 [pdflush]
> 4201 pts/1 R+ 0:00 grep D
> ... plus an Out of Memory kill of sshd. Second time around (logged in on
> the console rather than over ssh), it's just the same except it's hald
> that happens to get clobbered instead.
Are you saying that running in RAID0 mode with this card and motherboard
combination, you get a memory leak? Who is the culprit?
> Now that the presence or otherwise of a BBU has been ruled out along
> with OS, 3ware recommended kernel param tweaks, RAID level, LVM, slot
> speed, different but identical-spec hardware (both machine and card),
> what's left to try?
> I see there's a new firmware version out today (3ware codeset 126.96.36.199 -
> driver's still at 2.26.05.007 but the fw's updated to from 3.08.02.005
> to 3.08.02.007), so I guess I'll update it and push the whole thing back
> up the hill for another go.
I hope that fixes things for you.
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