If you have a server with SCSI drives and see a lot of EventIDs 11 and 15, this is a known issue and a hotfix has been released for Microsoft Windows Server 2003. See ME895573
to get the hotfix.
See the link to "EventID 15 from source Disk" for information on this event.
I had this error appear after one of our Win2K servers rebooted from a bugcheck. Our backup software could no longer access the tape autoloader (PowerVault 120T). This was caused by the autoloaders firmware being "locked" due to the nature of the reboot and not responding to the SCSI controller. Holding down the unit's eject button while rebooting reset the firmware and fixed the problem.
Got this (\Device\ScsiPort1) when my server crasehed. Tapes (autoloader) got locked in the drive (eject prevent). Each time the server restarted I would get this error, taking the tape drive offline. I watched the server at boot and the tape devices was active at boot time. Solution was to emergency eject the tape magazine (chisel) and reboot. Never got the error again.
I guess the autoloader was busy doing its own internal functions and not talking to the SCSI bus.
As per Microsoft: "Event ID 15 indicates that the device is not ready. This can be the result of SCSI host adapter configuration issues or other problems. Check with the manufacturer for updated firmware, drivers, or known issues. This could also indicate a malfunctioning device. This error occurs at the device level; the cluster software is not likely to be involved. Event ID 15 may also be accompanied by these error messages from the Cluster service:1038, 1036, 1069". See ME259237
for more details
This event may be completely unrelated with a real SCSI device/controller, as internally Windows NT designates IDE devices like CD drives and hard disks as SCSI. But the situation is the same, troubles with the drive or cabling. In particular for CD units, there is possible to be only a defective/dirty CD or dusty lens. Cleaning will help.
For a bad CD driver situation see ME150124
When a tape drive is involved maybe a bad tape or an access conflict as per ME136445
Source qntmdlt (tape driver). Appears when a DLT system is in "Offline". Start and stop services for particular software and restart the server that it is attached to. Verify that all services are stopped and restarted manually.