On Jan 22, 2006, at 20:25, Neil Brown wrote:
Changing the size of the devices is a separate operation that has
been supported for a while. For each device in turn, you fail it
and replace it with a larger device. (This means the array runs
degraded for a while, which isn't ideal and might be fixed one day).
Once all the devices in the array are of the desired size, you run
mdadm --grow /dev/mdX --size=max
and the array (raid1, raid5, raid6) will use up all available space
on the devices, and a resync will start to make sure that extra
space is in-sync.
One option I can think of that would make it much safer would be to
originally set up your RAID like this:
md3 (RAID-5)
__________/ | \__________
/ | \
md0 (RAID-1) md1 (RAID-1) md2 (RAID-1)
Each of md0-2 would only have a single drive, and therefore provide
no redundancy. When you wanted to grow the RAID-5, you would first
add a new larger disk to each of md0-md2 and trigger each resync.
Once that is complete, remove the old drives from md0-2 and run:
mdadm --grow /dev/md0 --size=max
mdadm --grow /dev/md1 --size=max
mdadm --grow /dev/md2 --size=max
Then once all that has completed, run:
mdadm --grow /dev/md3 --size=max
This will enlarge the top-level array. If you have LVM on the top-
level, you can allocate new LVs, resize existing ones, etc.
With the newly added code, you could also add new drives dynamically
by creating a /dev/md4 out of the single drive, and adding that as a
new member of /dev/md3.
Cheers,
Kyle Moffett
--
I lost interest in "blade servers" when I found they didn't throw
knives at people who weren't supposed to be in your machine room.
-- Anthony de Boer
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