Re: RAID-5 and mdadm --assemble troubleshooting
flat view
From: NeilBrown <hidden>
Date: 2011-03-21 22:28:08
On Mon, 21 Mar 2011 23:08:40 +0100 A J Wyborny [off-list ref] wrote:
Hi all, After exhausting my efforts with google searches and linux-raid IRC chats, I'm reaching out to you all for some help with why I can't assemble a broken RAID-5 configuration. My initial problem, I've determined, was caused by a faulty PCI-E SATA controller card. I would constantly lose access to my mounted RAID volume (/home) at random times and increasingly during high write accesses. In the past a reboot and running "mdadm --assemble --force --scan" would solve the issue. This time, no such luck. In the process of troubleshooting I also fat-fingered an "mdadm --assemble" command and lost the superblock of my /dev/sda1 partition, which isn't helping things either. The SMART status is clean on all disks. I really appreciate any thoughts/input you might have. -Adam Here's my setup: RAID-5 array with four 1.5TB disks (/dev/sda1, /dev/sdb1, /dev/sdd1, /dev/sde1) /dev/sdc is my root and swap partitions /dev/md0 should be mounted to /home Results: root@focalor:~# cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] unused devices: <none> root@focalor:~# mdadm -vv --assemble --force --scan mdadm: looking for devices for /dev/md0 mdadm: cannot open device /dev/sdc1: Device or resource busy mdadm: /dev/sdc1 has wrong uuid. mdadm: no RAID superblock on /dev/sda1 mdadm: /dev/sda1 has wrong uuid. mdadm: /dev/sde1 is identified as a member of /dev/md0, slot 3. mdadm: /dev/sdd1 is identified as a member of /dev/md0, slot 2. mdadm: /dev/sdb1 is identified as a member of /dev/md0, slot 1. mdadm: no uptodate device for slot 0 of /dev/md0 mdadm: added /dev/sdd1 to /dev/md0 as 2 mdadm: added /dev/sde1 to /dev/md0 as 3 mdadm: added /dev/sdb1 to /dev/md0 as 1 mdadm: failed to RUN_ARRAY /dev/md0: Input/output error
You are hitting an mdadm bug fixed in 2.6.9 by http://neil.brown.name/git?p=mdadm;a=commitdiff;h=4e9a6ff778cdc58dcc6897e74cf5ee1d3f73e1f7 What version of mdadm are you running? You can work around it by echo 1 > /sys/module/md_mod/parameters/start_dirty_degraded before running the 'mdadm -A' command.
dmesg output: http://pastebin.com/usrzvmpn mdadm -E output: http://pastebin.com/vnaamC75
It is OK - even encouraged - to include this content directly in the Email. That makes it easier to reference in a reply, should that be helpful. NeilBrown -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html