kernel tuning for HP Smart array 6i controller

[Loic Domaigne]

Hello Everybody,

We have a DL380 with a HP Smart array 6i Controller (version 2.58). We have currently two physical disks of 146,8Gb which are 1:1 mirrored.

We have installed Redhat Enterprise Linux AS 3, update 5. I'd like to optimize the DISK I/O by tuning the kernel/disk parameters.

Could you tell me which parameters should I tune? I plan to use IOzone or bonnie to measure the disk I/O performances.

BTW I heard that the performances of the Smart Array 6i controller are abysal. Is it true?

Kind Regards,
Loic.

[Stuart Browne · Accepted solution]

When compared to the remainder SA6 series of controllers (which have ample amounts of cache), yes. On it's own however, depending on the function of the server, it's usually quite adequate.

If you are really concerned about IO throughput, then you might look at one of the bigger controllers with larger caches.

As for OS tuning to get the most out of it, there's not really all that much you can do. Linux, by default, does agressive IO caching to get the most out of any IO path. Just so long as the system has plenty of RAM, you'll be fine.

Looking at the values in /proc/meminfo (or the output of top) will show you what I mean (see 'Cached' and 'Buffers').

[Alan_152]

according to nemeth, et al in Unix System Administration Handbook, don't do this as most people are not prepared to run the proper experiments to effectively judge changes in overall system performance. "I did X and the system 'feels' much faster".

[Loic Domaigne]

Hello Stuart,
Hello Alan,

thanks for your answers. Actually, even if the performances are not really improved, if my costumer "feels that it is faster", then I would be happy with that ;-)

Cheers,
Loic.

[Loic Domaigne]

Thanks to anyone that has participated.