From owner-freebsd-stable@FreeBSD.ORG Sat May 2 19:11:24 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 2615E1065670 for ; Sat, 2 May 2009 19:11:24 +0000 (UTC) (envelope-from alan.l.cox@gmail.com) Received: from mail-gx0-f167.google.com (mail-gx0-f167.google.com [209.85.217.167]) by mx1.freebsd.org (Postfix) with ESMTP id CDB1F8FC1E for ; Sat, 2 May 2009 19:11:23 +0000 (UTC) (envelope-from alan.l.cox@gmail.com) Received: by gxk11 with SMTP id 11so2094447gxk.19 for ; Sat, 02 May 2009 12:11:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:reply-to:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=g6KDFwm4YBnUeRB53XmdOP3Dx1YIt+CM197UrcrUlP4=; b=ob6LKAj5rzJWwhv5QKI90oJNBRsLqIzKEpV+ow9zaAc5qyG7GCotQMlw/9A3yPOIm+ a4T18AdRRWcWG5denayuO0FqDJ9UmUqP/PlEC3LOlHDolgaVyC4UuDjWuyWm8nphrc++ GVty0jd/z0MN85E/w25gGAamYyr3pQC0QjkAc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:reply-to:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; b=t/mlwgEeKUPFkh6PaPT0l2xXdSF0VbL9+2ouyfrJSqaw7lAyVD81HELNKKCreTk5r6 eq0PwWliDoOOlPFBGNqFEFpq416uFgpZsrHwIB3vkKWwAgkj5SdF/Pl38iZ0MyXxStt7 dbW/nx7lQPOGctb9jfMXvRGtmMIvNIlqr92xA= MIME-Version: 1.0 Received: by 10.151.128.11 with SMTP id f11mr8385199ybn.107.1241291483253; Sat, 02 May 2009 12:11:23 -0700 (PDT) In-Reply-To: References: <32A0BDD9-ACF8-43F4-8D2C-0FC151F1D7CB@cryptomonkeys.org> Date: Sat, 2 May 2009 14:11:23 -0500 Message-ID: From: Alan Cox To: Freddie Cash Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: FreeBSD Stable Subject: Re: current zfs tuning in RELENG_7 (AMD64) suggestions ? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: alc@freebsd.org List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 02 May 2009 19:11:24 -0000 On Fri, May 1, 2009 at 6:28 PM, Freddie Cash wrote: > On Fri, May 1, 2009 at 4:12 PM, Louis Kowolowski > wrote: > > On May 1, 2009, at 1:53 PM, Pete French wrote: > >> ... > >> The tuning isn't there to improve performance, it's there to prevent > >> the box going titus due to a panic when the ARC gets too big, and > >> you are missing the mian one, which is to limit the size of the ARC. > >> On recent versions of BSD (and you are running 7.2, so thats fine) then > >> the defaults for kmem size are fine, but you still need something like > >> this: > >> > >> vfs.zfs.arc_max="256M" > >> > >> In there to stop the ARC growing. thats the only tuning I have on > >> my 4 gig machine, which takes a steady stream of data and is used > >> for taking backup snapshots. ZFS is excellent, and for me is perfectly > >> stable, to the point where I am starting to roll it out to production > >> machines, with the above tuning. > >> > > I agree, although I'm using 384 instead of 256. My systems have been > > running in production for almost a year now w/o any ZFS issues. > > The exact value to use will depend on the system. Particularly on the > amount of RAM in the system, and what kmem_max is set to. A > "rule-of-thumb" we've been using is: > kmem_max should be half of the amount of RAM (or 1.5 GB as that's > the current max) This information is outdated. The current max in RELENG_7 for amd64 is ~3.75GB. Regards, Alan