Date: Thu, 09 Nov 2006 11:17:02 +0100 From: Ivan Voras <ivoras@fer.hr> To: freebsd-stable@freebsd.org Subject: Re: Dissapointing performance of ciss RAID 0+1 ? Message-ID: <eiuv6v$vgl$1@sea.gmane.org> In-Reply-To: <E1GhyUM-000Oct-6G@dilbert.firstcallgroup.co.uk> References: <E1GhyUM-000Oct-6G@dilbert.firstcallgroup.co.uk>
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Pete French wrote: > I've tried all the possible stripe sizes (128k gives the best performance) > but still I only get the above speeds. Just one of the 15k drives on it's > own performs better than this! I would expect the RAID-0 to give me at > least some speedup, or in the worst case be the same, surely ? The checklist for tuning usually goes like this: - Is the controller cache enabled? - Do you have the battery for it and is write cache enabled? (You won't make full use of the cache without the battery) - How does your performance compare when using dd on the raw devices (in order: da0, da0s1, da0s1a...) vs when using it on the file system? (Poor performance might indicate FS vs stripe alignment issues) - What does vmstat -i say while running your benchmarks? Any interrupt storms? - If all of this fails, post dmesg, maybe someone will notice something unusual.
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