Re: Linux hard drive/device nodes for a Postgres RAID array

On Thu, Nov 16, 2006 at 12:40:41PM -0800, Glen Parker wrote:
> But now, pull the drive from port 2 and boot the system. You will now
> have SDA,SDB,SDC. The kernel will now fail BOTH of the last two drives
> from the RAID array. The one that was SDC is gone, and obviously fails.
> The one that was SDD is now SDC, so its ID doesn't match what the
> kernel thought it should be, so it fails it too. If you kill the FIRST
> drive in the array, I believe the entire array becomes inoperable
> because of the resulting shift and ID mismatch.

Is that really so? AIUI the position of the disk in the array is stored
on the disk itself, so it should be able to handle disks moving around
no problem, have you tried it?

> So the question is, is there some way to "pin" a drive to a device
> mapping? In other words, is there a way to force the drive on port 0 to
> always be SDA, and the drive on port 2 to always be SDC, even if the
> drive on port 1 fails or is pulled?

I thought you could do this with options on the command-line, or using
udev. But I don't think it's actually necessary.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.