yum update installed kernel 2.6.32-504.8.1-el6.x86_64, and was correctly installed to /dev/sdb1/boot (ext3).
Physical drives on the machine (with expected/normal/previous device labels):
/dev/sdb1, ext3, 70 MB /dev/sda has three: sda1 ext3, 42 MB sda2 ext4, VolGroup00, 1TB LVM sda3 unallocated, 7 MB /dev/sdc1, ext3 2 TB
/etc/fstab looks like:
/dev/mapper/VolGroup00-root / ext4 /dev/sdb1 /boot ext3 /dev/sdc1 /data ext3
Now, for the problem description:
After a reboot, sda becomes sdb and sdb becomes sda, and sdc is MIA (cfdisk, fdisk and gparted report no such device). Needless to say, I haven't dis-/connected any additional devices.
Can someone make a suggestion as to what happened? This is behaviour I would expect after drive cables were moved around, or a new device were connected.
My only guess is the sdc drive has failed (since it doesn't appear in dmesg), however since it's after and sda and sdb, why would those two drives be re-ordered?
Additional details/background: Dell R2970, CentOS 5, last reboot ~March 19 perfectly normal, not sure if kernel was updated then, but probably as that is the only reason this machine would have been reboot.