From mboxrd@z Thu Jan 1 00:00:00 1970 From: Theodore Tso Subject: Re: thin provisioned LUN support & file system allocation policy Date: Fri, 7 Nov 2008 10:46:55 -0500 Message-ID: <20081107154655.GH9543@mit.edu> References: <20081107120534.GO21867@kernel.dk> <49143142.4010809@redhat.com> <20081107121934.GP21867@kernel.dk> <49145029.4040900@redhat.com> <20081107144311.GE9543@mit.edu> <4914568A.7090307@redhat.com> <49145E0C.4030705@hp.com> <49146031.70003@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Woodhouse , Ric Wheeler , Jens Axboe , Chris Mason , Dave Chinner , James Bottomley , linux-scsi@vger.kernel.org, linux-fsdevel@vger.kernel.org, Black_David@emc.com, "Martin K. Petersen" , Tom Coughlan , Matthew Wilcox To: jim owens Return-path: Content-Disposition: inline In-Reply-To: <49146031.70003@hp.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Fri, Nov 07, 2008 at 10:35:13AM -0500, jim owens wrote: > > I'm talking DISK wear not SSD. The array vendors who are causing > this problem are doing petabyte san devices, not SSDs. > > Rewriting the same sectors causes more bad block remaps > until the drive eventually runs out of remap space. How much of a disk wear factor is there with modern disk drives? The heads aren't touching the disk, and we have plenty of sectors which are constantly getting rewritten with traditional filesystems, with no ill effects as far as I know. For example, FAT filesystems, the superblock, block allocation bitmaps all are constantly getting rewritten today, and I haven't heard of disk manufacturers complaining that this is a horrible thing. - Ted