Differences

This shows you the differences between two versions of the page.

--- raid [2009/11/16 13:59] – 172.26.0.166
+++ raid [2009/11/16 14:25] – 172.26.0.166
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 ==== Repair RAID ====
+When a disk is failing you might see errors in the system logs from smartd like this:
+<file>Device: /dev/hda, 1 Offline uncorrectable sectors</file>
+In that case you need to replace the drive.  First, look at the RAID configuration to see which partitions are in use by which arrays.  For example:
+<code># cat /proc/mdstat
+Personalities : [raid1] [raid0]
+md3 : active raid1 hdd1[1] hda1[0]
+blocks [2/2] [UU]
+md1 : active raid1 hdd3[1] hda3[0]
+      26627648 blocks [2/2] [UU]
+md2 : active raid0 hdd5[1] hda5[0]
+      36868608 blocks 256k chunks
+md4 : active raid1 hdd6[1] hda6[0]
+      2168640 blocks [2/2] [UU]
+md0 : active raid1 hdd2[1] hda2[0]
+      30716160 blocks [2/2] [UU]
+unused devices: <none></code>
-Setting a disk faulty/failed:
+Because it is ''/dev/hda'' which was having problems, set all its RAID1 partitions as failed and remove them:
+<code># mdadm /dev/md0 --fail /dev/hda2 --remove /dev/hda2
+# mdadm /dev/md1 --fail /dev/hda3 --remove /dev/hda3
+# mdadm /dev/md3 --fail /dev/hda1 --remove /dev/hda1
+# mdadm /dev/md4 --fail /dev/hda6 --remove /dev/hda6</code>
-# mdadm --fail /dev/md0 /dev/hdc1
+Shut the server down and replace the faulty drive with a new one.  After booting your drive letters may have shifted around, so just be sure to verify which is which before proceeding.
+Clone the partition table from the good drive to the bad one:
+<code># sfdisk -d /dev/hda | sfdisk --force /dev/hdd</code>
+Verify the new partitions can be seen:
+<code># partprobe -s
+/dev/hda: msdos partitions 1 2 3 4 <5 6>
+/dev/hdd: msdos partitions 1 2 3 4 <5 6>
+/dev/sda: msdos partitions 1
+/dev/sdb: msdos partitions 1
+/dev/sdc: msdos partitions 1
+</code>
+You can now add the new partitions back to the arrays:
+<code># mdadm /dev/md0 --add /dev/hdd2
+# mdadm /dev/md1 --add /dev/hdd3
+# mdadm /dev/md3 --add /dev/hdd1
+# mdadm /dev/md4 --add /dev/hdd6</code>
-DO NOT run this every on a raid0 or linear device or your data is toasted!
-Removing a faulty disk from an array:
-# mdadm --remove /dev/md0 /dev/hdc1
 Clearing any previous raid info on a disk (eg. reusing a disk from another decommissioned raid array)