Presented here are some of the most common problems with SCSI controllers and devices,
such as CD-ROMs, hard drives, and tape drives. If you are having problems getting Linux to
recognize your drive or controller, read on. Let us again emphasize that most distributions use
a modularized kernel and that you might have to load a module supporting your hardware
during an early phase of the installation process. This might also be done automatically for
you.
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:
• An 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 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 boot from a partition using
cylinders numbered below 1024. See Section 3.1.7 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.
Chapter 3. Installation and Initial Configuration
77
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.
不错的东西，以后或许用的着，收藏起来
