From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stan Hoeppner Subject: Re: Software RAID checksum performance on 24 disks not even close to kernel reported Date: Wed, 06 Jun 2012 23:59:40 -0500 Message-ID: <4FD0353C.1050006@hardwarefreak.com> References: <20431.57247.76819.834529@tree.ty.sabi.co.UK> Reply-To: stan@hardwarefreak.com Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Igor M Podlesny Cc: Peter Grandi , Linux RAID List-Id: linux-raid.ids On 6/6/2012 10:41 PM, Igor M Podlesny wrote: > They try, for sure, but try is still a try. For e. g., you pvmove'd > your LVM with XFS from one RAID to another one having different > "layout", things can just stop working well all of the sudden. Filesystems that have zero awareness of the storage geometry have poor performance on striped RAID devices. XFS has excellent performance on striped RAID specifically due to this awareness. Now you describe this strength as a weakness due to a volume portability corner case no SA in his right mind would attempt. The proper way to do this is to perform an xfsdump of the filesystem to a file, create a new XFS with the proper stripe geometry in the new storage location (which takes all of 1 second BTW), then xfsrestore the dump file. And now you will say "Yes, but..." -- Stan