Date: Thu, 07 Jun 2007 11:15:18 +0200 From: Bernard Buri <berni@ask-us.at> Cc: freebsd-scsi@freebsd.org Subject: Re: Recommened U320 SCSI controller (pci-x)? Message-ID: <4667CCA6.3030508@ask-us.at> In-Reply-To: <20070607083147.GA25624@schottelius.org> References: <20070606143430.GA31380@schottelius.org> <466717E5.2070909@ask-us.at> <20070607083147.GA25624@schottelius.org>
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Nico -telmich- Schottelius wrote: > Bernard Buri [Wed, Jun 06, 2007 at 10:24:05PM +0200]: >> Hi! >> >> Not only for FreeBSD, I have the best experience with the mpt fusion >> based cards, concerning performance and compatibility/reliability. > > Do you have some card names? Searching for the 53c010 on the lsi logic > page was quite confusing, because it seems to link to other cards that > use the amr driver, which is another chip, afaiu. > >> Currently, we have a subversion server running FreeBSD 6.2 without any >> problems on an mpt based raid controller. I believe it is U160 though. > > Ok. We are trying to run a high-load mailserver over here and thus the > disk i/o is a big issue (and locking up the server a big problem). > > Nico > We have a "Feiertag==no one is in office" today, and there was a technical problem yesterday evening. Some servers are down obviously so I cannot lookup which product is built in exactly. I can find out tomorrow though. Are you looking for hardware raid, or do you want to do software raid ? Another question that comes to my mind: Did you analyze the disk i/o any further ? My experience with FreeBSD shows, that upgrading the main memory generously (2 or 4 GB) will allow the system to fill the buffer cache with file data, while leaving the "Namei lookup cache" constrained to some degree. If you run systat -vmstat 1, you can see everything on one place: 1.) On the bottom, you can see the actual disk utilization. 2.) Above, you can watch the "Namei" cache behaviour. 3.) On top, you see Free Memory, that is: memory that is not used at all So, on my Mac mini which has a very slow disk I face the following situation: I run du -h -d1 /usr/ports to fill the Namei cache. Now I watch the statistics in systat and run du again: 1.) I see actual disk i/o happening on my drive 2.) I see Namei cache hits dropping to ~45% 3.) I see about 300MB of memory unused. Most of the mailserver softwares are using many small files, and I guess that the lookup cache should improve the overall performance more than a fast drive. If you see low Namei hit rates, perhaps there is information available on how to tune the cache ?
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