Ubuntu raid - replacing drive?
The answer is "Yes, but..." -- You will probably need to tell the software RAID system (mdadm) that the drive has been replaced, following steps similar to these (I wasn't able to find a more ubuntu-specific way of doing this, but you may be able to do it through gnome-disk-utility as well).
The answer is "Yes, everything will work out as intended once you partition stuff." You can do it manually with fdisk or parted followed by mdadm, but the package gnome-disk-utility contains (is) the tool palimpsest which can do the whole job with GUI pointy-clicky:
- Select the RAID
- Edit Components
- Add Spare
and magic happens. A rebuild will take some not-insignificant time.
(Don't ask how I know.)
There is a trick to restore the partition table (and grub) to your new drive from the old:
dd if=/dev/sda of=/dev/sdb count=1 bs=512
where /dev/sda is the working old raid drive and /dev/sdb is the new replaced drive.
After forcing the re-reading of /dev/sdb partition table with hdparm -z /dev/sdb, you can add the new drive to the raid with mdadm /dev/mdX --add /dev/sdbX
Fast and without rebooting.
Disk Array Operation
Note: You can add, remove disks or set them as faulty without stopping an array.
- To stop an array, type:
$ sudo mdadm --stop /dev/md0
Where /dev/md0 is the array device.
- Remove a Disk from an Array
$ sudo mdadm --remove /dev/md0 /dev/sda1
Where /dev/md0 is the array device and /dev/sda is the faulty disk.
- Add a Disk to an Array
$ sudo mdadm --add /dev/md0 /dev/sda1
Where /dev/md0 is the array device and /dev/sda is the new disk.
Note: This is not the same as "growing" the array!
4.Start an Array, to reassemble (start) an array that was previously created:
$ mdadm --assemble --scan
mdadm will scan for defined arrays and start assembling it. Use this to track its status:
$ cat /proc/mdstat