Drive path problem - Linux Server v.6.3.4

Hi All,

I have a linux box with 8 drives which had been working normally for a long time. Suddenly, 4 of the 8 drives became unreachable. At the O/S, it would seem as though everything is okay, because I can see 8 device files all with the same permissions under /dev. There is, however, chatter like this in the messages log:

Sep 8 15:29:03 <> lin_taped[11073]: lin_taped: beginning failover for IBMtape1, hba 2, channel 0, id 1, lun 0
Sep 8 15:29:03 <> lin_taped[11073]: wake up device IBMtape1 with result -1
Sep 8 15:29:03 <> kernel: lin_tape: IBMtape1 failover failed.
Sep 8 15:29:03 <> kernel: lin_tape: IBMtape1-----AA173 unable to get inquiry page 83
Sep 8 15:29:03 <> kernel: lin_tape open failed: tape_inquiry_page: -5.
Sep 8 15:29:04 <> lin_taped[11073]: lin_taped: beginning failover for IBMtape1, hba 2, channel 0, id 1, lun 0
Sep 8 15:29:04 <> lin_taped[11073]: wake up device IBMtape1 with result -1
Sep 8 15:29:04 <> kernel: lin_tape: IBMtape1 failover failed.
Sep 8 15:37:06 <> kernel: lin_tape: the device IBMtape6-----AB0AA or another path to the same drive is already open.
Sep 8 15:37:53 <> kernel: lin_tape: the device IBMtape6-----AB0AA or another path to the same drive is already open.

The linux version is:

Linux seaputsmint01 2.6.18-348.3.1.el5 #1 SMP Tue Mar 5 13:18:54 EST 2013 ppc64

So even though the device files are out there, when I try to define paths to these drives I get the following:

09/08/2014 14:39:39 ANR2017I Administrator SCR issued command: DEFINE PATH
TSM_INT DR1 SRCTYPE=SERVER DESTTYPE=DRIVE LIBRARY=LTOLIB
DEVICE=/dev/IBMtape1 AUTODETECT=no (SESSION: 64)
09/08/2014 14:39:43 ANR8420E DEFINE PATH: An I/O error occurred while
accessing drive DR1. (SESSION: 64)

Any ideas what might be causing this or what else I might look at on the O/S to try and figure out what happened?

Sincere thanks,
C.J.