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Date:      Thu, 18 Jun 2009 08:25:47 -0700
From:      Freddie Cash <fjwcash@gmail.com>
To:        freebsd-fs@freebsd.org, FreeBSD Stable <freebsd-stable@freebsd.org>
Subject:   Re: ZFS performance on 7.2-release/amd64 low compared to UFS2 +  SoftUpdates
Message-ID:  <b269bc570906180825p1944ed04p77338dd9f7ec3b7@mail.gmail.com>
In-Reply-To: <E1MHCzU-000HX6-B9@dilbert.ticketswitch.com>
References:  <cf9b1ee00906171707r885b33csd4ec9026202bc63@mail.gmail.com> <E1MHCzU-000HX6-B9@dilbert.ticketswitch.com>

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On Thu, Jun 18, 2009 at 1:29 AM, Pete French <petefrench@ticketswitch.com>wrote:

> > All the ZFS tuning guides for FreeBSD (including one on the FreeBSD
> > ZFS wiki) have recommended values between 64M and 128M to improve
> > stability, so that what I went with. How much of my max kmem is it
> > safe to give to ZFS?
>
> If you are on amd64 then don't tune it, it will tune itself. If you
> are on i386 (or an earlier verions of amd64) then 128M on a 2 gig machine
> should be OK, assuming you have kmem_size_max set to the full 1500 odd.
> Those are numbers which come up time and time again - I ran reliably with
> them for ages, until the latest -STABLE.
>

My "rule of thumb" for 32-bit i386 systems has been to:  - assign half of
RAM to kmem (up to the max of ~1500 on 7.0/7.1)
  - assign half of kmem to zfs_arc_max

So far, for my workloads (nfs/cifs file servers, cups print servers, rsync
servers, kde4 desktop), it's worked well.

-- 
Freddie Cash
fjwcash@gmail.com



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