Tape Backup Not Recognized

[Karl Zander]

We have a PE 1950 running CentOS 4.6.  We have PowerVault 122T (DLT 
160 autoloader) tape backup attached to it. The colo center recently 
moved some equipment and the PowerVault stopped working.  It is 
powered on and the SCSI cable is connected.

The device does not seem to show up as an attached device.

[root at advocate1 bru]# cat /proc/scsi/scsi
Attached devices:
Host: scsi2 Channel: 00 Id: 08 Lun: 00
   Vendor: DP       Model: BACKPLANE        Rev: 1.05
   Type:   Enclosure                        ANSI SCSI revision: 05
Host: scsi2 Channel: 02 Id: 00 Lun: 00
   Vendor: DELL     Model: PERC 5/i         Rev: 1.03
   Type:   Direct-Access                    ANSI SCSI revision: 05


dmesg shows this
[root at advocate1 bru]# dmesg | grep scsi
scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36
scsi1 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.36
scsi2 : LSI Logic SAS based MegaRAID driver

which shows the SCSI card is recognized.

We can do modprobe for sg

modprobe sg
Attached scsi generic sg0 at scsi2, channel 0, id 8, lun 0,  type 13
Attached scsi generic sg1 at scsi2, channel 2, id 0, lun 0,  type 0

but without the PV 122T being recognized we can't work with it.  And 
the  /dev/st0 device does not show up either.

I will likely have to go hands on at the colo. Just trying to get 
ideas on what I am looking for.  It could be as simple as a cable not 
connected properly, but beyond that, what am I looking for?

--Karl