From mboxrd@z Thu Jan 1 00:00:00 1970 From: Iain Rauch Subject: Reshape speed Date: Wed, 14 Jan 2009 00:05:32 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids Hi, I've recently assembled a new RAID 6. When I assembled it, I had 3 disks and one missing. I then added two disks. The first disk was used to recover the originally missing disk. The second disk is being used to grow the array. The recovery went at about 45MB/s but the reshape is only around 11MB/s. CPU usage is as follows: 12.8 1398 root [md1_raid5] 2.0 7996 root [md1_reshape] Memory usage is as follows: Type Percent Capacity Free Used Size Physical Memory 18% 2.97 GB 661.03 MB 3.62 GB - Kernel + applications 6% 218.21 MB - Buffers 0% 7.67 MB - Cached 12% 435.14 MB Disk Swap 0% 0.00 KB 0.00 KB 0.00 KB Disk Swap 0% 0.00 KB 0.00 KB 0.00 KB #uname -a Linux edna 2.6.24-etchnhalf.1-amd64 #1 SMP Tue Dec 2 17:21:26 UTC 2008 x86_64 GNU/Linux Why is the reshape so much slower? Where's the bottleneck? Also, would it have been possible to do both these operations in one step? -- Thanks in advance, Iain P.S. The reason the array was assembeled with a disk missing is explained in other thread "RAID 6 recovery (it's not looking good)" which isn't finished yet.