From owner-freebsd-fs@FreeBSD.ORG Wed Mar 21 23:56:51 2012 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id AF1671065674 for ; Wed, 21 Mar 2012 23:56:51 +0000 (UTC) (envelope-from andy@time-domain.co.uk) Received: from mail.time-domain.co.uk (81-179-248-237.static.dsl.pipex.com [81.179.248.237]) by mx1.freebsd.org (Postfix) with ESMTP id 36E888FC08 for ; Wed, 21 Mar 2012 23:56:50 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mail.time-domain.co.uk (8.14.3/8.14.3) with ESMTP id q2LNundm005416 for ; Wed, 21 Mar 2012 23:56:49 GMT Date: Wed, 21 Mar 2012 23:56:49 +0000 (GMT) From: andy thomas X-X-Sender: andy-tds@mail.time-domain.co.uk To: freebsd-fs@freebsd.org Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed X-Virus-Scanned: clamav-milter 0.97.1 at mail X-Virus-Status: Clean Subject: ZFS read/write performance slows with time X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Mar 2012 23:56:51 -0000 A server running 64-bit FreeBSD 8.0 boots from a SATA disk and then mounts a ZFS mirror consisting of two SAS disks plus one spare. Immediately after booting, the filesystem is fast and responsive and 'zpool iostat -v tank' reports read and write disk bandwidths of over 22 MB. But over a period of time, this performance begins to deteriorate and after 180 days of uptime this server, which is running mail, samba and webmail servers in 3 separate jails, really struggles especially the IMAP daemon. zpool iostat -v reports a maximum read bandwidth of around 2MB and a write bandwidth of 143 KB maximum. Rebooting the system restores normal performance but the cycle gradually repeats itself. I can't see anything wrong in any log and the system has 12 GB of memory and a 2 Ghz quad-core Xeon CPU so it isn't under-resourced. At boot time ZFS reports its version as being 13 - could the problem be due to a memory leak or some other issue with early versions of ZFS that have since been fixed in later FreeBSD releases? Andy