Date: Sat, 20 Sep 2008 21:35:20 +0300 From: Ruslan Kovtun <yalur@mail.ru> To: freebsd-fs@freebsd.org Subject: Re: zfs benchmarks and 7 disk raidz oddity Message-ID: <200809202135.20730.yalur@mail.ru> In-Reply-To: <48D4C2AA.8080000@modulus.org> References: <48D4C2AA.8080000@modulus.org>
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Hi. Thank you very much, very useful information. It is interesting when we can use this on 7.x? В сообщении от Суббота 20 сентября 2008 Andrew Snow написал(a): > Hi all, > > I am running 8-CURRENT with ZFS patches on a 3ghz Core2Duo with Intel > P45 chipset. I took some benchmarks of ZFS on six old SATA disks and > one PATA, onboard controllers only, and I expect you are interested to > see the results. The disks range in size from 200gb to 320gb. > > I tried several configurations with quick and dirty testing. Listed > below is the sequential megabytes/sec rating as measured by dd bs=1m for > a 10GB file. All ZFS settings were left at their defaults. > > > Conf Write Read (MB/s) > ------------------------------------ > 7 disk RAIDZ2 220 305 > 7 disk RAIDZ1 84 361 > 7 disk striped 318 409 > 7 disk stripe copies=2 140 164 > > 6 disk RAIDZ2 173 260 > 6 disk RAIDZ1 238 307 > 6 disk striped 280 346 > 6 disk 2xRAIDZ1 striped 188 251 > 6 disk striped mirrors 164 323 > 6 disk stripe copies=2 151 179 > > > A few notes: > > 1. using copies=2 is a nice way to be able to get RAID1-like mirroring > reliability but on an odd number of disks. However you take a > noticeable performance penalty: Write speed is fine but read speed is > almost half of what RAID0+1 achieved. > > 2. RAIDZ1 and RAIDZ2 are fast and efficient. However in total it caused > the system to use almost all of one CPU core during writing. > > 3. There seemed to be a bug with 7 disks and RAIDZ1 - the write > performance was terrible! When I ran "gstat" I noticed it was spending > much time writing to only two disks most of the time, which became a > serious bottleneck - the worst write score of the lot. Read was fine. > Perhaps the algorithm isn't optimised for choosing parity locations out > of exactly 7 disks? > > > > - Andrew > > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org" -- ________________ Ruslan Kovtun mailto: yalur@mail.ru mob: +380503557878, +380919015095 ICQ: 277696182
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