From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Meier Subject: Recovery after failed chunk size change Date: Thu, 31 Mar 2016 21:33:38 +0200 Message-ID: <56FD7B92.1030102@ferienwohnung-altenbeken.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed 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 there, I tried to do a chunk size change from 4096k to 64k on a 7-disk RAID6 array. I am using Debian Jessie with kernel 3.16 and mdadm 3.3.2. After I initiated the change the process staled immediately. I could watch it in /proc/mdadm that there has not been any progress at all. The backup-file hasn't been touched for days now. So I decided to backup all data from that device in case it isn't starting at next reboot. Accidentally the system was restarted before the backup was finished. And now the array is not assembling any more, even with the correct --backup-file. I get "mdadm: Failed to restore critical section for reshape, sorry.". So the first question is: How can I access the data again? I think there is no damage at this time- I appended an output from --examine at the end of this message. All seven drives giving me the same output in all relevant topics. Especially "Chunk Size", "New Chunksize" and "Reshape pos'n" is all the same. What is the best way now that I do not damage any data? Second question: Is the problem with the level change a known bug? Thanks for reading! -- /dev/disk/by-partlabel/hyper_TA_1: Magic : a92b4efc Version : 1.2 Feature Map : 0x5 Name : hyper:TA (local to host hyper) Raid Level : raid6 Raid Devices : 7 Avail Dev Size : 3434725376 (1637.80 GiB 1758.58 GB) Array Size : 8586813440 (8189.02 GiB 8792.90 GB) Data Offset : 147456 sectors Super Offset : 8 sectors Unused Space : before=147368 sectors, after=0 sectors State : clean Internal Bitmap : 8 sectors from superblock Reshape pos'n : 0 New Chunksize : 64K Update Time : Thu Mar 31 17:57:01 2016 Bad Block Log : 512 entries available at offset 72 sectors Checksum : e7172c1f - correct Events : 527046 Layout : left-symmetric Chunk Size : 4096K Device Role : Active device 5 Array State : AAAAAAA ('A' == active, '.' == missing, 'R' == replacing)