[CentOS] 3Ware 9550SX and latency/system responsiveness

[Feizhou]

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 
> /mnt/raidtest
> 
> (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?

Bug report...

> 
> I see there's a new firmware version out today (3ware codeset 9.4.1.3 - 
> 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.