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.=20 It is interesting when we can use this on 7.x? =D0=92 =D1=81=D0=BE=D0=BE=D0=B1=D1=89=D0=B5=D0=BD=D0=B8=D0=B8 =D0=BE=D1=82 = =D0=A1=D1=83=D0=B1=D0=B1=D0=BE=D1=82=D0=B0 20 =D1=81=D0=B5=D0=BD=D1=82=D1= =8F=D0=B1=D1=80=D1=8F 2008 Andrew Snow =D0=BD=D0=B0=D0=BF=D0=B8=D1=81=D0=B0= =D0=BB(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=3D1m 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=3D2 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=3D2 151 179 > > > A few notes: > > 1. using copies=3D2 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" =2D-=20 ________________ Ruslan Kovtun=20 mailto: yalur@mail.ru mob: +380503557878, +380919015095 ICQ: 277696182
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