Brad Campbell wrote:

G'day all,

I've got 3 arrays here. A 3 drive raid-5, a 10 drive raid-5 and a 15
drive raid-6. They are all currently 250GB SATA drives.

I'm contemplating an upgrade to 500GB drives on one or more of the
arrays and wondering the best way to do the physical swap.

The slow and steady way would be to degrade the array, remove a disk,
add the new disk, lather, rinse, repeat. After which I could use mdadm
--grow. There is the concern of a degraded array here though (and one of
the reasons I'm looking to swap is some of the disks have about 30,000
hours on the clock and are growing the odd defect).

Assuming hotswap and for maximum uptime/minimal exposure to risk... a while back
there was a discussion of a fiddly way that involved adding a disk, making a
mirror, removing the old disk, breaking the mirror. ( See archive for details)

I was more wondering about the feasibility of using dd to copy the drive
contents to the larger drives (then I could do 5 at a time) and working
it from there.

Err, if you can dd the drives, why can't you create a new array and use xfsdump
or equivalent? Is downtime due to copying that bad?

David