From owner-freebsd-hackers@FreeBSD.ORG Sat Jan 23 09:25:23 2010 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 81A07106566B for ; Sat, 23 Jan 2010 09:25:23 +0000 (UTC) (envelope-from alexander@leidinger.net) Received: from mail.ebusiness-leidinger.de (mail.ebusiness-leidinger.de [217.11.53.44]) by mx1.freebsd.org (Postfix) with ESMTP id 383668FC14 for ; Sat, 23 Jan 2010 09:25:22 +0000 (UTC) Received: from outgoing.leidinger.net (pD9E2CA42.dip.t-dialin.net [217.226.202.66]) by mail.ebusiness-leidinger.de (Postfix) with ESMTPSA id 6302484515E; Sat, 23 Jan 2010 10:25:18 +0100 (CET) Received: from unknown (unknown [192.168.2.110]) by outgoing.leidinger.net (Postfix) with ESMTP id 4DDD4235134; Sat, 23 Jan 2010 10:25:15 +0100 (CET) Date: Sat, 23 Jan 2010 10:25:13 +0100 From: Alexander Leidinger To: jhell Message-ID: <20100123102513.00001f67@unknown> In-Reply-To: References: <7f14551c1001190119x46c6b04dx2362cd1252f0d81@mail.gmail.com> <7f14551c1001190216w49814186n1ada2b721380502b@mail.gmail.com> <4B55C5A6.2020109@DataIX.net> <20100120111433.25801pnmhrxnirok@webmail.leidinger.net> X-Mailer: Claws Mail 3.7.2cvs15 (GTK+ 2.16.0; i586-pc-mingw32msvc) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-EBL-MailScanner-Information: Please contact the ISP for more information X-EBL-MailScanner-ID: 6302484515E.588E7 X-EBL-MailScanner: Found to be clean X-EBL-MailScanner-SpamCheck: not spam, spamhaus-ZEN, SpamAssassin (not cached, score=-1.44, required 6, autolearn=disabled, ALL_TRUSTED -1.44) X-EBL-MailScanner-From: alexander@leidinger.net X-EBL-MailScanner-Watermark: 1264843518.83811@DyA0xFoM55/qUskiJjnXPw X-EBL-Spam-Status: No X-Mailman-Approved-At: Sat, 23 Jan 2010 12:45:46 +0000 Cc: FreeBSD Hackers , Artem Belevich Subject: Re: Setting "zfs_arc_max" value in FreeBSD 8. X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 23 Jan 2010 09:25:23 -0000 On Fri, 22 Jan 2010 21:39:48 -0500 jhell wrote: > > On Fri, 22 Jan 2010 11:47, fbsdlist@ wrote: > >>> Anyone know if it is adjustable on a system with 1024MB of ram ? > >>> Is this just being auto calculated by some other value ? > > > > You may want to make sure that vm.kmem_size is set to a value much > > larger than vfs.zfs.arc_max. Default value may be too small to allow > > such a large ARC. > > > > On a side note, I'm not sure that ZFS is a good match for system > > with only 1G of RAM. By trial and error on my box with 8G or memory > > I've figured out that I need to set arc_max ~1G below physical > > memory size to avoid lockups under load. YMMV. > > > > ZFS on this box with 1G has been quite enjoyable actually. With the > settings I have posted I have not had any lockup on stable/7 and no > sudden freezes or waits for transfers. So this entirely thus far has > been a godsend. I had even put this thing through some of the > tortures that others have posted to the list and not come up with the > same results but better. There is obviously a lot of variables in > this between hardware and configurations used so the results are > minimal in comparison. With ZFS in place on this machine it performs > a little bit under specs for the hardware but I wouldn't expect > anything less for such a file-system. You may want to switch to fletcher4 checksums. This is the default in Solaris and 8.0 now. I didn't merge this change to 7-stable as I didn't took the time to analyze if the change for the default has some unwanted implications for existig pools. I have a 9-current box with 1GB RAM and ZFS which shows the slow-down after some hours of running (and doing things) too. It would be good to make a list of OS versions and if there are slowdowns or not (anyone with time out there to have a look at the mails and get this info out of the mails / people?). Maybe it is related to changes not in ZFS... Bye, Alexander.