From owner-freebsd-hackers@FreeBSD.ORG Fri Jan 4 02:32:35 2008 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 AE2DF16A418 for ; Fri, 4 Jan 2008 02:32:35 +0000 (UTC) (envelope-from anderson@freebsd.org) Received: from ns.trinitel.com (186.161.36.72.static.reverse.ltdomains.com [72.36.161.186]) by mx1.freebsd.org (Postfix) with ESMTP id 8042A13C442 for ; Fri, 4 Jan 2008 02:32:35 +0000 (UTC) (envelope-from anderson@freebsd.org) Received: from neutrino.vnode.org (r74-193-81-203.pfvlcmta01.grtntx.tl.dh.suddenlink.net [74.193.81.203]) (authenticated bits=0) by ns.trinitel.com (8.14.1/8.14.1) with ESMTP id m042WTt9018680; Thu, 3 Jan 2008 20:32:30 -0600 (CST) (envelope-from anderson@freebsd.org) Message-ID: <477D9AB8.8050805@freebsd.org> Date: Thu, 03 Jan 2008 20:32:24 -0600 From: Eric Anderson User-Agent: Thunderbird 2.0.0.9 (X11/20071227) MIME-Version: 1.0 To: "Daan Vreeken [PA4DAN]" References: <200801032352.56491.Danovitsch@vitsch.net> <20080103233019.GE17445@rebooten.de> <200801040046.25465.Danovitsch@vitsch.net> In-Reply-To: <200801040046.25465.Danovitsch@vitsch.net> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-2.1 required=5.0 tests=AWL,BAYES_00 autolearn=ham version=3.1.8 X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on ns.trinitel.com Cc: Markus Boelter , FreeBSD-Hackers@freebsd.org Subject: Re: mksnap_ffs time 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: Fri, 04 Jan 2008 02:32:35 -0000 On 01/03/08 17:46, Daan Vreeken [PA4DAN] wrote: > On Friday 04 January 2008 00:30:20 you wrote: >> Hi! >> >>> 1) Is anyone else seeing this? >> As far as I know, this is somehow related to the SoftUpdates, but I am not >> 100% sure. Look at the mailinglist archives, there was a discussion a few >> months ago about the same topic as far as I remember. >> >> Please note that according to >> http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/snapshots.html >> a filesystem can only have 20 snapshots! :-) > > Hmm.. Then at least time spent per snapshot isn't going to get much worse than > it is today ;-) > Too bad this limitation isn't mentioned in 'man 8 mksnap_ffs'. If this > limitation is still there, I think it deserves a place in the manual. The limitation is still there, and probably should be mentioned in the manual - good point. The time is spent making copies of all the cylinder groups, which there are a *lot* of on a 700GB file system. When UFS snapshots were developed, 4-20GB file systems were pretty big. Over time, this problem is going to just get worse. :( The only way to help it, is to use some custom newfs options to reduce the number of cylinder groups, but it won't buy you much. Snapshots also impede on your general file system performance. In FreeBSD 7, you could use ZFS, which would give you the power and control you need (plus FreeBSD 7 has many many performance improvements). Eric