Next: 2.5.2.3 Problems with SCSI Up: 2.5.2 Hardware problems Previous: 2.5.2.1 Isolating hardware problems

### 2.5.2.2 Problems recognizing hard drive or controller

When Linux boots, you should see a series of messages on your screen such as:

`Console: colour EGA+ 80x25, 8 virtual consoles
Serial driver version 3.96 with no serial options enabled
tty00 at 0x03f8 (irq = 4) is a 16450
tty03 at 0x02e8 (irq = 3) is a 16550A
lp_init: lp1 exists (0), using polling driver
...`

Here, the kernel is detecting the various hardware devices present on your system. At some point, you should see the line

`Partition check:`

followed by a list of recognized partitions, for example:

`Partition check:
hda: hda1 hda2
hdb: hdb1 hdb2 hdb3`

If, for some reason, your drives or partitions are not recognized, then you will not be able to access them in any way.

There are several things that can cause this to happen:

- Hard drive or controller not supported. If you are using a hard drive controller (IDE, SCSI, or otherwise) that is not supported by Linux, the kernel will not recognize your partitions at boot time.

- Drive or controller improperly configured. Even if your controller is supported by Linux, it may not be configured correctly. (This is particularly a problem for SCSI controllers; most non-SCSI controllers should work fine without any additional configuration).

  Refer to the documentation for your hard drive and/or controller for information on solving these kinds of problems. In particular, many hard drives will need to have a jumper set if they are to be used as a ``slave'' drive (for example, as the second hard drive). The acid test for this kind of condition is to boot up MS-DOS, or some other operating system, known to work with your drive and controller. If you can access the drive and controller from another operating system, then it is not a problem with your hardware configuration.

  See Section 2.5.2.1, above, for information on resolving possible device conflicts, and Section 2.5.2.3, below, for information on configuring SCSI devices.

- Controller properly configured, but not detected. Some BIOS-less SCSI controllers require the user to specify information about the controller at boot time. Section 2.5.2.3, below, describes how to force hardware detection for these controllers.

- Hard drive geometry not recognized. Some systems, such as the IBM PS/ValuePoint, do not store hard drive geometry information in the CMOS memory, where Linux expects to find it. Also, certain SCSI controllers need to be told where to find drive geometry in order for Linux to recognize the layout of your drive.

  Most distributions provide a bootup option to specify the drive geometry. In general, when booting the installation media, you can specify the drive geometry at the LILO boot prompt with a command such as:

  `boot: linux hd=,,`

  where , , and correspond to the number of cylinders, heads, and sectors per track for your hard drive.

  After installing the Linux software, you will be able to install LILO, allowing you to boot from the hard drive. At that time, you can specify the drive geometry to the LILO installation procedure, making it unnecessary to enter the drive geometry each time you boot. See Chapter 4 for more about LILO.

Next: 2.5.2.3 Problems with SCSI Up: 2.5.2 Hardware problems Previous: 2.5.2.1 Isolating hardware problems