ZFS makes SSDs faster than memory!

[Rafael Henrique Faria]

On Fri, Jul 23, 2010 at 09:15, Ivan Voras <ivoras at 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