[CentOS] ZFS on Linux in production?

Sat Oct 26 23:38:04 UTC 2013
George Kontostanos <gkontos.mail at gmail.com>

On Sat, Oct 26, 2013 at 4:36 PM, Ray Van Dolson <rayvd at bludgeon.org> wrote:

> On Thu, Oct 24, 2013 at 01:59:15PM -0700, John R Pierce wrote:
> > On 10/24/2013 1:41 PM, Lists wrote:
> > > Was wondering if anybody here could weigh in with real-life experience?
> > > Performance/scalability?
> >
> > I've only used ZFS on Solaris and FreeBSD.    some general
> observations...
> >
> > 1) you need a LOT of ram for decent performance on large zpools. 1GB ram
> > above your basic system/application requirements per terabyte of zpool
> > is not unreasonable.
> >
> > 2) don't go overboard with snapshots.   a few 100 are probably OK, but
> > 1000s (*) will really drag down the performance of operations that
> > enumerate file systems.
> >
> > 3) NEVER let a zpool fill up above about 70% full, or the performance
> > really goes downhill.
>
> Have run into this one (again -- with Nexenta) as well.  It can be
> pretty dramatic.  We tend to set quotas to ensure we don'get exceed 75%
> or so max, but....
>
>
> We maybe getting a bit off topic here but on that subject we have noticed
a significant degrade in performance on systems running at 75-80 % of their
pool capacity. I understand that the nature of COW will increase
fragmentation. On large storages though 70% out of 100TB means that you
have to always maintain 30TB free which is not a small number in terms of
cost per TB.

-
George Kontostanos
---