From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Tweedie Subject: Re: [linux-lvm] EXT2 to EXT3 LVM volume on Redhat Message-ID: <20020623164611.A1993@redhat.com> References: <003401c20c0f$23a7afb0$0300000a@STATION> <000c01c20ccf$fcac9e90$0201a8c0@fosi> Mime-Version: 1.0 Content-Disposition: inline In-Reply-To: <000c01c20ccf$fcac9e90$0201a8c0@fosi>; from steve.wray@paradise.net.nz on Thu, Jun 06, 2002 at 08:31:30AM +1200 Sender: linux-lvm-admin@sistina.com Errors-To: linux-lvm-admin@sistina.com Reply-To: linux-lvm@sistina.com List-Help: List-Post: List-Subscribe: , List-Unsubscribe: , List-Archive: Date: Mon Jun 24 08:41:01 2002 List-Id: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-lvm@sistina.com Cc: Stephen Tweedie , Steve Wray Hi, On Thu, Jun 06, 2002 at 08:31:30AM +1200, Steve Wray wrote: > /dev/system/home /home ext3 data=journal 1 2 > > Its the bomb. I have a hell of a lot of dynamic data > in that /home so in event of a crash there was a big > chance of corruption. Not Any More!!!!! > 8-) I'm not quite sure why people think that data=journal is any "safer" than the default data=ordered mode. In fact, data=ordered could well be safer simply because the default mode is probably in use on more systems, and so is better tested. :-) data=journal writes the data to the journal as well as the metadata, but *both* ordered and data modes flush data to disk carefully as part of their transaction commit. If you create new files with the default of data=ordered, there is still an absolute guarantee that a transaction commit will show all the data safe on disk, and you will never see stale data blocks show up on disk after a crash. Only the looser "data=writeback" mode of ext3 relaxes this guarantee and makes data writes independent of metadata writes, as they are for most other filesystems. Cheers, Stephen