On Monday, I installed Debian on a PE2800, stacked it full of SCSI hard drives and configured it as an iSCSI RAID device using tgt. It all worked fantastically, and karma naturally stepped in to balance things.
tgt does not have a Debian init script, so I wrote one and rebooted the server to check it works. Now, when the RAID card initializes the SCSI disks, I get an obscure error, saying that 'SCSI Channel-0: 4 is not responding'. It does not say any RAIDs are degraded or missing. I haven't allowed the server to boot yet. When I go into the RAID card settings, I go to 'Configure -> View/Add Configuration', it freezes at 'Finding Disk Capacity of Channel-0 Target-06'. None of the disks are flashing failures, and it sounds like there's two faults here.
There are two RAIDs configured, a two-disk RAID1 for boot, and a 6-disk RAID5 for data. We were literally about to send this machine to our factory in another country because it appeared to be ready (it was running without a single issue for two days straight), so this problem is not particularly welcome right now! Where should I start?
Edit: I think I've found something. I mixed and matched 10K and 15K RPM disks in the RAID5. The system booted okay so the mirror RAID is fine. There is no data on the RAID5 so I'm going to recreate it using some spare disks.