Date: Sun, 08 May 2005 23:22:44 +0200 From: Willem Jan Withagen <wjw@withagen.nl> To: Steven Hartland <killing@multiplay.co.uk> Cc: freebsd-current@freebsd.org Subject: Re: Very low disk performance Highpoint 1820a Message-ID: <427E8324.8010905@withagen.nl> In-Reply-To: <002b01c553db$5e167340$b3db87d4@multiplay.co.uk> References: <069901c54bfd$2967ba40$7f06000a@int.mediasurface.com> <427D5AA0.1080609@withagen.nl> <002b01c553be$93a5b790$b3db87d4@multiplay.co.uk> <427E05D2.2060706@digiware.nl> <002b01c553db$5e167340$b3db87d4@multiplay.co.uk>
next in thread | previous in thread | raw e-mail | index | archive | help
Steven Hartland wrote: >> Still I would argue that if you do not use a write size larger than >> what you have as real memory, that buffering in real memory is going >> to play a role.... > > > I think you miss read all the details here Willem. Sorry about that, if that is the case. > Original values: > Write: 150Mb/s > Read: 50Mb/s > Current value after tweeking, RAID stripe size, vfs.read_max and > MAXPHYS ( needs more testing now due to scotts warning ) > Write: 150Mb/s > Read: 200Mb/s > > Note: The test size was upped to 10Gb to avoid caching issues. That would certainly negate my assumption 10G is enough to regularly flush the buffer. >> Other than that I find 50Mb/s is IMHO reasonable high value for a >> RAID5 in writting. But it would require substantial more organised >> testing. DD is nothing more than a very crude indication of what to >> expect in real life. > > > dd was uses as it is a good quick indication of baseline sequential file > access > speed and as such highlighted a serious issue with the original > performance. That is well phrased English for what I was trying to say. I'm glad to see that it worked for you. And I'm certainly impressed by the numbers... This is on a 4 disk RAID5 with one hot spare??? --WjW
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?427E8324.8010905>