On 8/4/06, Jason Murray <[EMAIL PROTECTED]> wrote:
I previously had a bit of trouble with my raid array. That is now cleared
up and I need to replace one HD of the mirrored set. Never having done
this I thought I'd check here to see if there was any advice on HD selection.
Natrually the replacement HD will have to be at least the same size as the
original. But are there any restrictions on HD geometry?
Sector size is all that matters. Must be greater than or equal. The
unused space is truncated. I don't beleive the other geometries matter
-- except that your partitions must lie on cylinder boundries.
Different geometries will mean you will end up wasting a few sectors.
Example below.
It naively makes sense to me to try match things as closely as possible.
Or am I way off base here?
You're fine. When I run out of spares i do a lot of research and buy
bulk of new disks, and begin transitioning as they die, or more
commonly (as i did in example below) just transition my data to a new
raid (using backups!!), and use the old disks as spares again.
With most raid levels, you're only as efficient as your weakest link,
so theres no point in buying an exceptionaly faster disk of the same
geometry unless you replace them both.
Here is an example of a disk partition of the wrong geometry (sd2 is a spare):
raid1 (root)raid2: Component /dev/sd0p being configured at row: 0 col: 0
Row: 0 Column: 0 Num Rows: 1 Num Columns: 4
Version: 2 Serial Number: 20060601 Mod Counter: 964
Clean: Yes Status: 0
raid2: Component /dev/sd1p being configured at row: 0 col: 1
Row: 0 Column: 1 Num Rows: 1 Num Columns: 4
Version: 2 Serial Number: 20060601 Mod Counter: 964
Clean: Yes Status: 0
raid2: Component /dev/sd2p being configured at row: 0 col: 2
Row: 0 Column: 2 Num Rows: 1 Num Columns: 4
Version: 2 Serial Number: 20060601 Mod Counter: 964
Clean: Yes Status: 0
raid2: Component /dev/sd3p being configured at row: 0 col: 3
Row: 0 Column: 3 Num Rows: 1 Num Columns: 4
Version: 2 Serial Number: 20060601 Mod Counter: 964
Clean: Yes Status: 0
WARNING: truncating disk at r 0 c 2 to 17767763 blocks.
