From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anshuman Aggarwal Subject: What was the default chunk size in previous versions of mdadm? Is there a way to set data/super offset? Trying to recreate a raid 5 md with all spares Date: Mon, 25 Jun 2012 12:31:56 +0530 Message-ID: References: Mime-Version: 1.0 (Apple Message framework v1278) 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 ---I hope the subject is clearer now, in line with the mailing list expectations ---- Hi, I have a 6 device raid 5 array which had 1 disk go bad and then due to a power outage, the machine shutdown and when it started all the disks were showing up as spares with the following mdadm -E output (sample for one given below and full for all devices attached). This md device was part a Physical Volume for a LVM Volume Group. I am trying to recreate the array using mdadm --create --assume-clean using 1 device as missing. I am checking if the device is getting created correctly by checking the UUID of the created device which would match if the device gets created correctly. I have tried a few combinations of the disk order that I believe is right however I think I'm getting tripped up by the fact that the mdadm I used to create this md device was some 2.x series and now we are on 3.x (and I may have taken some of the defaults originally which I don't' remember) What all 'defaults' have changed over the versions so I can try those? Like chunk size? Can we manually configure the super/data offset? Are those significant when we do an mdadm --create --assume-clean? Thanks, Anshu /dev/sda5: Magic : a92b4efc Version : 1.2 Feature Map : 0x0 Array UUID : b480fe0c:c9e29256:0fcf1b0c:1f8c762c Name : GATEWAY:RAID5_500G Creation Time : Wed Apr 28 16:10:43 2010 Raid Level : -unknown- Raid Devices : 0 Avail Dev Size : 976768002 (465.76 GiB 500.11 GB) Used Dev Size : 976765954 (465.76 GiB 500.10 GB) Data Offset : 2048 sectors Super Offset : 8 sectors State : active Device UUID : a8499a91:628ddde8:1cc8f4b9:749136f9 Update Time : Sat May 19 23:04:23 2012 Checksum : 9950883c - correct Events : 1 Device Role : spare Array State : ('A' == active, '.' == missing)