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SCSI Problems

SCSI is one of the most versatile interfaces, and it pays for that versatility in potential problems. Linux is usually good about reporting problems with SCSI devices, although the error messages may leave you wondering about the real cause of the problem.

Table 3.2 lists many of the common SCSI errors and their probable causes. Find the message that closely matches the error message Linux displays in this table to determine your corrective steps.

Table 3.2. Common SCSI errors and their probable causes.

Error Cause
SCSI device at all possible IDs One or more devices is at the same SCSI ID as the controller. Check and change device IDs. Controllers should be ID 7.
Sense errors Probably caused by bad termination. Check that both ends of the SCSI chain are terminated. If that is not the problem, the cable is likely at fault.
Timeout errors Usually caused by a DMA, IRQ, or I/O address conflict. See the previous section for more information.
SCSI adapter not detected The BIOS is disabled or the SCSI adapter is not recognized by the kernel. Check the drivers.
Cylinders beyond 1024 Your disk has more than 1,024 cylinders, which the PC BIOS can’t handle. Linux can use more than 1,024 cylinders, but it can’t boot from a partition that extends across that cylinder boundary.
CD-ROM drive not recognized Some CD-ROMs require a CD in the drive to be recognized properly. Insert a CD and reboot.

Booting Linux

If you have installed Linux and the system won’t boot properly from your hard disk, it may be a problem with LILO or with the partitions. If you created a boot floppy, boot from that. If that boots without a problem, check the partition table by executing fdisk. Make sure the Linux partition is active. If it is and you still can’t boot from the hard disk, boot from the floppy and run LILO again to configure the boot sector. See Chapter 4 for more information on LILO.

A problem sometimes occurs when Linux can’t find the main Linux partition. Boot from the floppy and hold down the Shift or Control key. This produces a menu that allows you to specify the boot device explicitly. This problem can usually be corrected with LILO.

Summary

Much of this chapter was familiar to you if you have installed Linux before, although some users really don’t know what was going on during the automated installation script. Knowing the process and staying on top of it helps to prevent problems with the Linux installation.

The next step is using LILO to configure the boot system properly, a commonly misunderstood and misused process. The next chapter looks at LILO. For more information related to the subject of installation and associated subjects, you can jump to other chapters:

To learn how to use your new Linux system, read Part II, starting with Chapter 6, “Getting Started.”
To learn about installing and configuring X so you can use a graphical interface, see Chapter 22, “Installing and Configuring XFree86.”
To learn how to manage your system, read Part VI, starting with Chapter 32, “System Administration Basics.”


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