Re: help please, can't mount/recover raid 5 array
From: Dave Cundiff <hidden>
Date: 2013-02-10 22:01:30
On Sun, Feb 10, 2013 at 4:05 PM, Phil Turmel [off-list ref] wrote:
Hi Daniel, On 02/10/2013 04:36 AM, Daniel Sanabria wrote:quoted
On 10 February 2013 09:17, Daniel Sanabria [off-list ref] wrote:quoted
Hi Mikael, Yes I did. Here it is:[trim /]quoted
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/dev/sda3: Magic : a92b4efc Version : 0.90.00=====================^^^^^^^quoted
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UUID : 0deb6f79:aec7ed69:bfe78010:bc810f04 Creation Time : Thu Dec 3 22:12:24 2009 Raid Level : raid5 Used Dev Size : 255999936 (244.14 GiB 262.14 GB) Array Size : 511999872 (488.28 GiB 524.29 GB) Raid Devices : 3 Total Devices : 3 Preferred Minor : 2 Update Time : Sat Feb 9 16:09:20 2013 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0 Checksum : 8dd157e5 - correct Events : 792552 Layout : left-symmetric Chunk Size : 64K=====================^^^quoted
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Number Major Minor RaidDevice State this 0 8 3 0 active sync /dev/sda3 0 0 8 3 0 active sync /dev/sda3 1 1 8 18 1 active sync /dev/sdb2 2 2 8 34 2 active sync /dev/sdc2From your original post:quoted
/dev/md2: Version : 1.2====================^^^quoted
Creation Time : Sat Feb 9 17:30:32 2013 Raid Level : raid5 Array Size : 511996928 (488.28 GiB 524.28 GB) Used Dev Size : 255998464 (244.14 GiB 262.14 GB) Raid Devices : 3 Total Devices : 3 Persistence : Superblock is persistent Update Time : Sat Feb 9 20:47:46 2013 State : clean Active Devices : 3 Working Devices : 3 Failed Devices : 0 Spare Devices : 0 Layout : left-symmetric Chunk Size : 512K====================^^^^quoted
Name : lamachine:2 (local to host lamachine) UUID : 48be851b:f0210b64:e9fbefdf:24c84c5f Events : 2 Number Major Minor RaidDevice State 0 8 3 0 active sync /dev/sda3 1 8 18 1 active sync /dev/sdb2 2 8 34 2 active sync /dev/sdc2I don't know what possessed you to use "mdadm --create" to try to fix your system, but it is almost always the wrong first step. But since you scrambled it with "mdadm --create", you'll have to fix it with "mdadm --create". mdadm --stop /dev/md2 mdadm --create --assume-clean /dev/md2 --metadata=0.90 \ --level=5 --raid-devices=3 --chunk=64 \ /dev/sda3 /dev/sdb2 /dev/sdc2
It looks like your using a dracut based boot system. Once you get the array created and mounting you'll need to update /etc/mdadm.conf with the new array information and run dracut to update your initrd with the new configuration. If not problems could crop up down the road.
Then, you will have to reconstruct the beginning of the array, as much as 3MB worth, that was replaced with v1.2 metadata. (The used dev size differs by 1472kB, suggesting that the new mdadm gave you a new data offset of 2048, and the rest is the difference in the chunk size.) Your original report and follow-ups have not clearly indicated what is on this 524GB array, so I can't be more specific. If it is a filesystem, an fsck may fix it with modest losses. If it is another LVM PV, you may be able to do a vgrestore to reset the 1st megabyte. You didn't activate a bitmap on the array, so the remainder of the new metadata space was probably untouched.
If the data on this array is important and without backups it would be a good idea to image the drives before you start doing anything else. Most of your data can likely be recovered but you can easily destroy it beyond conventional repair if your not very careful at this point. According to the fstab in the original post it looks like its just an ext4 filesystem on top of the md. If that is the case an fsck should get you going again after creating the array. You can try a regular fsck but your superblock is most likely gone. A backup superblock if needed is generally accessible by adding -b 32768 to the fsck. Hopefully you didn't have many files in the root of that filesystem. They are all most likely going to end up as random numbered files and directories in lost+found. -- Dave Cundiff System Administrator A2Hosting, Inc http://www.a2hosting.com