Running Linux, 5th Edition - Matthias Kalle Dalheimer [46]
The Linux SCSI HOWTO contains much useful information on SCSI devices in addition to that listed here. SCSIs can be particularly tricky to configure at times.
It might be a false economy, for example, to use cheap cables, especially if you use wide SCSI. Cheap cables are a major source of problems and can cause all kinds of failures, as well as major headaches. If you use SCSI, use proper cabling.
Here are common problems and possible solutions:
A SCSI device is detected at all possible IDs
This problem occurs when the system straps the device to the same address as the controller. You need to change the jumper settings so that the drive uses a different address from the controller itself.
Linux reports sense errors, even if the devices are known to be error-free
This can be caused by bad cables or by bad termination. If your SCSI bus is not terminated at both ends, you may have errors accessing SCSI devices. When in doubt, always check your cables. In addition to disconnected cables, bad-quality cables are a common source of troubles.
SCSI devices report timeout errors
This is usually caused by a conflict with IRQ, DMA, or device addresses. Also, check that interrupts are enabled correctly on your controller.
SCSI controllers using BIOS are not detected
Detection of controllers using BIOS will fail if the BIOS is disabled, or if your controller's "signature" is not recognized by the kernel. See the Linux SCSI HOWTO for more information about this.
Controllers using memory-mapped I/O do not work
This happens when the memory-mapped I/O ports are incorrectly cached. Either mark the board's address space as uncacheable in the XCMOS settings, or disable the cache altogether.
When partitioning, you get a warning "cylinders > 1024," or you are unable to boot from a partition using cylinders numbered above 1023
BIOS limits the number of cylinders to 1024, and any partition using cylinders numbered above this won't be accessible from the BIOS. As far as Linux is concerned, this affects only booting; once the system has booted, you should be able to access the partition. Your options are to either boot Linux from a boot floppy or to boot from a partition using cylinders numbered below 1024. See "Creating the Boot Floppy or Installing GRUB," earlier in this chapter.
CD-ROM drive or other removable media devices are not recognized at boot time
Try booting with a CD-ROM (or disk) in the drive. This is necessary for some devices.
If your SCSI controller is not recognized, you may need to force hardware detection at boot time. This is particularly important for SCSI controllers without BIOS. Most distributions allow you to specify the controller IRQ and shared memory address when booting the installation medium. For example, if you are using a TMC-8xx controller, you may be able to enter:
boot: linux tmx8xx=interrupt,memory-address
at the LILO boot prompt, where interrupt is the controller IRQ, and memory-address is the shared memory address. Whether you can do this depends on the distribution of Linux you are using; consult your documentation for details.
Problems Installing the Software
Installing the Linux software should be trouble-free if you're lucky. The only problems you might experience would be related to corrupt installation media or lack of space on your Linux filesystems. Here is a list of common problems:
System reports "Read error, file not found" or other errors while attempting to install the software
This is indicative of a problem with your installation medium. If you are installing from floppy, keep in mind that floppies are quite susceptible to media errors of this type. Be sure to use brand-new,