How many ram...

Karli Sjöberg karli.sjoberg at slu.se
Wed Jan 14 18:03:13 UTC 2015


Den 14 jan 2015 18:28 skrev Freddie Cash <fjwcash at gmail.com>:
>
> On Wed, Jan 14, 2015 at 9:00 AM, Albert Shih <Albert.Shih at obspm.fr> wrote:
>
> >  Le 14/01/2015 à 10:50:18-0600, Linda Kateley a écrit
> > > I will say one more thing.. I also have a customer who uses zfs for
> > > security camera storage. The cameras deliver 100's of k bytes per
> > > minute... But they save the data for a very very very long time. That
> > > kind of system would need very little ram(maybe 8GB) but lots and lots
> > > of disk.
> >
> > Thanks you very much.
> >
> > May I ask you something (feel free to not answer of course ). I saw on your
> >
> > > >> 32GB ram. http://kateleyco.com/?p=815
> >
> > you have install I quote
> >
> >   «hey will have 252 4TB drives in 6 45-drive chassis with multiple
> >   controllers»
> >
> > do you have any idea how many pool they have ? how many disk they put in
> > one raid ? how many raid they put in one pool ?
> >
> > Actually I've one server a very big pool (I known some tell me it's too
> > big) with 72 disks in 6 raidz2.
> >
> > ​We have two storage systems with 90 harddrives each (2 TB drives).  These
> are setup with 2 45-drive 4U JBOD chassis each, and a 2U head unit with
> SSDs for the OS and L2ARC/ZIL, and the SATA controllers.  The way the
> hardware is configured, they can each handle another 2 JBOD chassis without
> daisy-chaining anything.
>
> ​Using 6-disk raidz2 vdevs, for a total of 15 raidz2 vdevs per storage
> pool.​
>
> ​These are backup systems and an off-site replication system, so storage
> throughput and IOps wasn't super critical, while storage space and
> manageability were.  They only have gigabit NICs, and can saturate those
> while running backups or "zfs send" / "zfs recv".
>
> They do have 128 GB of RAM, though, more as a "get it now while it's cheap
> instead of waiting until we need it" than anything.  And they have dual
> 8-core AMD Opteron CPUs (again, more as a "they're inexpensive now, so get
> as much as we can afford" than any real need for it).
>
> One of them has dedupe enabled (yeah, yeah, we know, we're moving away from
> it, it's actually the last one with it enabled),

But what about all of the savings you were benefitting from? Wasn't it like 10x dedup savings or something, I know I've asked before at the forums but a person forgets... What's made you change your mind?

/K (a.k.a Sebulon)

> and actually does use the
> RAM for DDT storage in the ARC.  The other one doesn't have dedupe enable,
> and most of the RAM sits "idle". ​
>
> --
> Freddie Cash
> fjwcash at gmail.com
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