Hi all, I apologize for asking a Linux question here in the postgres
list, but I figure somebody here must know the answer, or a better place
to ask it.
I am building an x86_64 postgres server (see, it isn't JUST about Linux
:-) with SATA drives and I want to use software RAID for my postgres
storage.
When Linux boots, it finds all the drives in the system and assigns
device numbers to them, apparently in the order found. So, the first
drive (on SATA port 0 for example) become SDA, the second becomes SDB,
and so on. If you have say, four drives, on ports 0,1,2,3, everything
works fine and you get SDA,SDB,SDC,SDD.
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.
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?
-Glen
