[CentOS] Software RAID Level 1, smartd and changing dev numbers

Wed Feb 16 17:00:27 UTC 2011
James Smallacombe <james at sicom.com>

We have about 50 CentOS servers with software RAID level 1 (mirroring). 
Each week, we swap out one of the drives (the one in the second of four
hot-swap bays, only the first two of which contain drives) on each server
and take them offsite for safekeeping.

The problem is, the kernel seemingly randomly switches between /dev/sdb
and /dev/sdc for these devices.  This makes the process slower by
requiring more manual input where a script(s) could otherwise suffice.

It also confuses smartd, which AFAIK, needs the correct device names to
report accurately.

Ideally, we'd like to force the OS at some level to always see these
devices as /dev/sda and /dev/sdb.  If not, is there at least some way to
configure smartd to be "smart" and recognize which devices are in use?