From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Leslie Rhorer" Subject: RE: RAID halting Date: Fri, 24 Apr 2009 23:32:58 -0500 Message-ID: <20090425043301801.UXMF6537@cdptpa-omta02.mail.rr.com> References: <49F21B75.7060705@sauce.co.nz> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <49F21B75.7060705@sauce.co.nz> Sender: linux-raid-owner@vger.kernel.org To: 'Linux RAID' List-Id: linux-raid.ids > >> Quad core Xeon 2.8GHz md RAID6 of 16 x 750GB. Delete 20GB file: > >> > >> time rm -f dump > >> > >> real 0m1.849s > >> user 0m0.000s > >> sys 0m1.633s > > > > 3.2 GHz AMD Athlon 64 x 2 RAID6 of 10 x 1T: > > > > RAID-Server:/RAID/Recordings# ll sizetest.fil > > -rw-rw-rw- 1 lrhorer users 27847620608 2009-04-24 03:21 sizetest.fil > > RAID-Server:/RAID/Recordings# time rm sizetest.fil > > > > real 0m21.503s > > user 0m0.000s > > sys 0m6.852s > > > > See what I mean? 'Zero additional activity on the array other than the > rm > > task. We'll see what happens with XFS. > > Hi Leslie, > > Regarding my previous post, I missed your comment about later growing > the array, so what I said about mkfs.xfs automatically calculating the > correct swidth/sunit sizes is correct initially, but once you grow the > array, you will need to manaully calculate new values and these are > applied as mount options. > > I grew a 3 disk RAID5 to 4 disks and the write performance was > definitely inferior until this was done. Well, write performance is not generally a big issue with this array, as it does vastly more reading than writing. In any case, as long as the parameters can be updated with a mount option, it's not a really big deal. What about the read performance? Is it badly impacted for pre-existing files? The files on this system are very static. Once they are edited and saved, they're pretty much permanent.