From owner-freebsd-stable@FreeBSD.ORG Thu May 9 15:06:28 2013 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id 1FEB8647 for ; Thu, 9 May 2013 15:06:28 +0000 (UTC) (envelope-from dan@dan.emsphone.com) Received: from email2.allantgroup.com (email2.emsphone.com [199.67.51.116]) by mx1.freebsd.org (Postfix) with ESMTP id E0E5BCC0 for ; Thu, 9 May 2013 15:06:27 +0000 (UTC) Received: from dan.emsphone.com (dan.emsphone.com [172.17.17.101]) by email2.allantgroup.com (8.14.5/8.14.5) with ESMTP id r49F0ToW079077 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 9 May 2013 10:00:29 -0500 (CDT) (envelope-from dan@dan.emsphone.com) Received: from dan.emsphone.com (smmsp@localhost [127.0.0.1]) by dan.emsphone.com (8.14.7/8.14.6) with ESMTP id r49F0THX004849 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Thu, 9 May 2013 10:00:29 -0500 (CDT) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.14.7/8.14.6/Submit) id r49F0TZd004848; Thu, 9 May 2013 10:00:29 -0500 (CDT) (envelope-from dan) Date: Thu, 9 May 2013 10:00:29 -0500 From: Dan Nelson To: Benjamin Adams Subject: Re: recommended memory for zfs Message-ID: <20130509150029.GA20797@dan.emsphone.com> References: <518BA237.3030700@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <518BA237.3030700@gmail.com> X-OS: FreeBSD 9.1-STABLE User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: clamav-milter 0.97.8 at email2.allantgroup.com X-Virus-Status: Clean X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7 (email2.allantgroup.com [172.17.19.78]); Thu, 09 May 2013 10:00:30 -0500 (CDT) X-Spam-Status: No, score=-3.9 required=5.0 tests=ALL_TRUSTED,BAYES_00, RP_MATCHES_RCVD autolearn=ham version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on email2.allantgroup.com X-Scanned-By: MIMEDefang 2.73 Cc: freebsd-stable@freebsd.org X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 09 May 2013 15:06:28 -0000 In the last episode (May 09), Benjamin Adams said: > Hello zfs question about memory. > I heard zfs is very ram hungry. > Service looking to run: > - nginx > - postgres > - php-fpm > - python > > I have a machine with two quad core cpus but only 4 G Memory > > I'm looking to buy more ram now. > What would be the recommend amount of memory for zfs across 6 drives on > this setup? As much as is reasonable to purchase. Postgres would probably appreciate the memory more than ZFS. You can run ZFS on memory-limited machines (I've gone as far down as 256MB), but the critical part is running a 64-bit kernel. ZFS does a lot of kernel malloc/free operations, and address space fragmentation on a 32-bit system will eventually cause a panic when ZFS can't malloc a contiguous 128k chunk. -- Dan Nelson dnelson@allantgroup.com