Date: Fri, 23 Jul 2010 09:35:31 -0300 From: Rafael Henrique Faria <rafaelhfaria@cenadigital.com.br> To: freebsd-fs@freebsd.org Subject: Re: ZFS makes SSDs faster than memory! Message-ID: <AANLkTi=41MVXRSYzdxTCu6MO9nh3OW6SA5PgkkR4s=eh@mail.gmail.com> In-Reply-To: <i2c14p$g4f$1@dough.gmane.org> References: <4C496EB0.7050004@fsn.hu> <i2c14p$g4f$1@dough.gmane.org>
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On Fri, Jul 23, 2010 at 09:15, Ivan Voras <ivoras@freebsd.org> wrote: > On 07/23/10 12:28, Attila Nagy wrote: > > Hi, > > > > I've came across a strange issue. On a file server (ftp/http/rsync) > > there is a dual SSD based L2ARC configured for a pool of 24 disks: > > > fetch -o /dev/null -4 > > > http://ftp.fsn.hu/pub/CDROM-Images/opensolaris/osol-0906-106a-ai-sparc.iso > > /dev/null 100% of 493 MB 11 MBps > > If I understand your setup and your benchmark correctly, you are saying > you have achieved 11 megabytes / s performance out of a volume of 24 > RAIDZ2 drives split into two parts (so it's like RAID 60). Doesn't this > number seem extremely low to you, considering that (if recent models) > each of your drives can probably pull at least 70 MB/s? > > > Hi, I'm not so sure, but some time ago, reading the ZFS documentation from Sun, I noticed that with a lot of disks, is better to use a lot of raidz too... with your 24 disks, I think that you could get better security (don't know about performance) with 4 raidz2 (6 disks on each one) And, again, not sure here, but I think that more then one raidz pool, will be like a JBOD, and not a stripe (60). -- Rafael Henrique da Silva Faria
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