[Beowulf] RAID question

[Gerald Henriksen]

On Wed, 18 Mar 2015 14:00:15 -0700, you wrote:

>The disk errors were a red herring. The system had a Seagate USB disk 
>plugged into it which I was not aware of.  (It was less not obvious 
>because of the rats nest of cables behind it.)  This disk's partition 
>table was marked bootable - even though there was nothing on that disk 
>which would have supported a boot.  This was the disk that was showing 
>up as /dev/sdb.  When CentOS booted normally it was automatically 
>mounting this disk, which is why there was no mention of it in 
>/etc/fstab.  However, nothing was using this disk.  It looks like at 30 
>minute intervals the OS "pinged" the device to see if it was still 
>there, and the enclosure/disk did not fully support whatever command was 
>being used for this operation, resulting in the sense error messages in 
>the log files. When the rescue DVD was
>used it saw this device, created /dev/sda for it (yes, device names were 
>exchanged in the two environments) and didn't mount it.

Linux does not guarantee device names to remain the same, which is why
partitions are usually mounted via a unique partition ID in /etc/fstab