Partitioning with fdisk
This section applies only if you chose to use fdisk to partition your system. If are not using fdisk, please skip to the section called Disk Partitioning for automatic partitioning or the section called Partitioning Your System for partitioning with Disk Druid.
 | Caution |
|---|---|
Unless you have previously used fdisk and understand how it works, we do not recommend that you use it. Disk Druid is easier to understand than fdisk. To exit fdisk, click Back to return to the previous screen, deselect fdisk, and then click Next. |
SRM Partitioning Requirements
When you allow the Red Hat Linux installation program to partition for you (automatic partitioning), the installation program will handle certain special partitioning requirements for SRM. Disk Druid is also aware of SRM's partitioning requirements and will partition your system accordingly. If you use fdisk to partition manually, however, you will need to be aware of these issues, since you will need to take care of them yourself. Special partitioning issues for SRM include the following:
You will need to use BSD-style disklabels. When you use fdisk in the graphical installation program, it will start in BSD disklabel mode.
You will need to leave unallocated space at the beginning of your hard drive.
You will need to use BSD-style disklabels because of aboot's partitioning requirements. When you are using the SRM firmware to boot Linux, you are using the aboot boot loader. The aboot program supports the creation of bootable block devices and contains a program which can load Linux kernels from a filesystem that is bootable by SRM.
The aboot program does not understand DOS-style partition tables. You will need to use BSD-style disklabels, which aboot does understand.
BSD-style disk labeling is different in certain ways from standard fdisk-style partitioning (used on x86 installations) in the following ways:
The partitions are identified by letters (a, b, c...) instead of numbers.
The partition types are different. For example, instead of using "83" and "82" to correspond to "Linux" and "Linux Swap," respectively, ext2 partitions are identified as "8"; the swap partition is "1".
You can have a maximum of eight partitions (a to h) per drive.
Partition types must be explicitly set after creation. The BSD disklabel program uses a default partition type of unknown which causes the Disk Setup portion of the installation program not to see the partitions.
Another requirement for partitioning is that you provide initial unallocated space at the beginning of the hard drive. The initial unallocated space is unallocated disk space that is not explicitly allocated to any label other than the "whole disk" label. This space should be approximately 1 MB to 10 MB (2048 to 20480 sectors), depending on exactly what configuration of aboot you are using.
The unallocated disk space provides space at the very beginning of the hard drive for aboot to write the boot block and object file that allows booting to kernels located within the disk labels. For more information on the process aboot uses to boot, please see the SRM Firmware HOWTO at the following URL:
http://www.alphalinux.org/faq/srm.html |
 | Warning |
|---|---|
To provide the initial unallocated space, you will need to start your partitions at cylinder 2. If you do a workstation- or server-class installation and allow the installation program to partition for you, the installation program will provide the initial unallocated space. If you are using Disk Druid, Disk Druid knows about this requirement, and it will not allow you to start the partitions at cylinder 1 during manual partitioning. If you are using fdisk, however, you will need to remember to start your partitions at cylinder 2. |
Using fdisk
If you have chosen to use fdisk, the next screen will prompt you to select a drive to partition using fdisk.
Once you have chosen which drive to partition, you will be presented
with the fdisk command screen. If you do not
know what command to use, type
The following table provides the most common fdisk commands.
Table 4-2. fdisk commands
| Command | What it Does |
|---|---|
| b | enters BSD disklabel command line mode |
| m | displays help |
| p | displays the current partition table |
| d | deletes a partition |
| n | creates a new partition |
| w | writes the partition table to disk |
| t | sets the type of partition |
| L | displays the list of partition types |
| q | quits fdisk |
You will need to be aware of a few issues regarding partitioning with fdisk. First, Linux fdisk creates partitions of type unknown by default. When you create partitions, do not forget to change swap partitions to type Linux swap, and Linux partitions to type ext2 using the t command. The value for the Linux swap type is 1; ext2 partitions are 8. For other partition types, use the L command to see a list of partition types and values.
Linux allows up to four (4) partitions on one disk. If you wish to create more than that, one (and only one) of the four may be an extended partition, which acts as a container for one or more logical partitions. Since it acts as a container, the extended partition must be at least as large as the total size of all the logical partitions it is to contain.
It is a good idea to write down which partitions (for example, /dev/sda2) are meant for which filesystems (for example, /usr) as you create each one.
When you are finished making partitions, type
When you are finished partitioning your disks, press Next; you may see a message indicating that the installation program needs to reboot. This is a normal occurrence after changing a disk's partition data; it usually happens if you created, changed or deleted any extended partitions. After you press OK, your machine will reboot and the installation will begin again. Repeat the same installation steps you performed earlier until you reach the Partition Disks dialog; then simply choose Next.
 | Please Note |
|---|---|
None of the changes you make take effect until you save them and exit fdisk using the w command. You can quit fdisk at any time without saving changes using the q command. |
After you have partitioned your drive(s), click Next. Then you will need to use Disk Druid to assign mount points to the partitions you just created with fdisk.
You will not be able to add new partitions using Disk Druid, but you will be able to edit mount points for the partitions you have already created.
For each partition you created with fdisk, click on the Edit button, choose the appropriate mount point for that partition from the pulldown menu, and click on OK.