From owner-freebsd-hackers@FreeBSD.ORG Tue Nov 23 22:02:32 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 8944F1065674 for ; Tue, 23 Nov 2010 22:02:32 +0000 (UTC) (envelope-from kraduk@gmail.com) Received: from mail-gw0-f54.google.com (mail-gw0-f54.google.com [74.125.83.54]) by mx1.freebsd.org (Postfix) with ESMTP id 42B168FC20 for ; Tue, 23 Nov 2010 22:02:31 +0000 (UTC) Received: by gwj21 with SMTP id 21so405476gwj.13 for ; Tue, 23 Nov 2010 14:02:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:cc:content-type; bh=fwPpmOG6vusU9xT0FlBjAbkIJExJr+qZpYW8cUxrSxg=; b=HzGG2LJA1WFnQ9NBWL+zfUBG7xO1G72enL46yoSQU2zJ4p/LCFkDxtxI8f8uAHb+fs e3SpihEnTPjYpd5NbI+1+BnDD0+7xTCwge58H8v3AJpBMEaPSvJfYwieOL1v4vq5xWpl knqwy7kGUj7Glz2kCcOl5HVaPMrt7LkBmFw/E= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; b=RMXYbYm64ccyJCNCggSnNOj+bmDUOJxRYwZsWXLTR+zPCoPhTuSRMsylz2GEmzttj+ 4fBT9ivvUMieHqt4MdYmj56W86LKHslJ+tmYe9JTe4k+aFSWwLh5XmJLADAsTotZZDq9 NnikBCSVArAwvYDwp/NDCJnBC+v8xR8DYeVd8= MIME-Version: 1.0 Received: by 10.216.196.156 with SMTP id r28mr7288102wen.29.1290549750944; Tue, 23 Nov 2010 14:02:30 -0800 (PST) Received: by 10.216.37.132 with HTTP; Tue, 23 Nov 2010 14:02:30 -0800 (PST) In-Reply-To: <20101123194950.GB74848@pix.net> References: <4CEC0A27.8080900@smartt.com> <20101123194950.GB74848@pix.net> Date: Tue, 23 Nov 2010 22:02:30 +0000 Message-ID: From: krad To: Kurt Lidl X-Mailman-Approved-At: Tue, 23 Nov 2010 22:14:43 +0000 Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-hackers@freebsd.org, Chris St Denis Subject: Re: UFS Snapshots and iowait 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: Tue, 23 Nov 2010 22:02:32 -0000 On 23 November 2010 19:49, Kurt Lidl wrote: > On Tue, Nov 23, 2010 at 10:38:31AM -0800, Chris St Denis wrote: > > Is this just due to the very high io bandwidth usage associated with > > making a snapshot, or does the creation of this snapshot completely > > block IO writes for around 5 minutes? > > It blocks updates to the filesystem while during part of the > snapshot process. > > See the comments in /usr/src/sys/ufs/ffs/ffs_snapshot.c > > I found using UFS snapshots on a production fileserver untenable > during normal working hours. I have a backup fileserver that I > rsync the files to, and then use the UFS snapshots there. > > > Any suggested workarounds? I already bumped up the number of Apache > > slots to 166% but it looks like I would have to increase the number much > > more to use that as a primary solution. > > Use ZFS. The way snapshots work there, they are nearly instantanous > to create, and you are not limited to 20 snapshots per filesystem. > > -Kurt > _______________________________________________ > freebsd-hackers@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-hackers > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@freebsd.org" > I can testify zfs snapshots are very usable, as we use it to backup our mysql and oracle databases. Issue a write lock, flush, snap, remove lock, backup snapshot All takes a few seconds and is fairly seamless