From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: high throughput storage server? Date: Thu, 24 Mar 2011 13:07:53 -0400 Message-ID: <20110324170753.GA29482@infradead.org> References: <4D868C36.5050304@hardwarefreak.com> <20110321024452.GA23100@www2.open-std.org> <4D875E51.50807@hardwarefreak.com> <20110321221304.GA900@www2.open-std.org> <20110322094658.GA21078@cthulhu.home.robinhill.me.uk> <20110322101403.GA9329@www2.open-std.org> <4D89B519.3020907@hardwarefreak.com> <4D8A1D9B.7020100@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4D8A1D9B.7020100@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: Joe Landman Cc: Mdadm List-Id: linux-raid.ids On Wed, Mar 23, 2011 at 12:19:39PM -0400, Joe Landman wrote: > The issue though is that xfs stores journals internally by default. > You can change this, and in specific use cases, an external journal > is strongly advised. This would be one such use case. In general if you have enough spindles, or an SSD for the log for an otherwise disk based setup the external log will always be a win. For many workloads log will be the only backwards seeks. This is slightly offtopic here through, because as Joe already sais corretly it won't matter too much for a read heavy workload. > Unfortunately, xfs snapshots have to be done via LVM2 right now. My > memory isn't clear on this, there may be an xfs_freeze requirement > for the snapshot to be really valid. e.g. That's not needed anymore for a long time now - device mapper now calls the freeze_fs method to invoke exactly the same code to freeze the filesystem.