Installation - Configure Partitioning and RAID

Overview

For some installations, you may want to define a custom partition scheme instead of using the default. Typically, custom partitioning is required for:

• Software RAID
• Creating a separate /home partition
• Data redundancy with DRBD

Select Advanced Partitioning

If you do not wish to use the default partitioning scheme on your system, then select advanced partitioning in the installation wizard (see screenshot).

	Warning!

The tool for creating partitions will appear at a later stage in the installer. Continue with the rest of the installation wizard after selecting the partition type on this screen.

Using the Disk Druid Partition Tool

When the installer displays a disk partitioning setup page, select the Disk Druid option on this screen. The documentation for this partitioning tool is available here:

• Disk Druid Documentation

Example: Software RAID 1

Using software RAID is a common way to protect against a hard disk failure. Here is a step-by-step guide to implement Software RAID 1 on regular IDE hard disks.

Preparing the Hardware

For software RAID 1, you need two hard disks. Since the RAID partitions on both the hard disks must be of equal size, it is a good idea to use two hard disks with (roughly) the same storage capacity. In our example, we are using two IDE disks on two different disk controllers. These hard disks are detected in Linux as:

• /dev/hda
• /dev/hdc

Deleting Existing Partitions

Some hard disks may have partitions already defined. These existing partitions (if any) must first be deleted.

• Use the tab key to move to the main window (one tab after highlighting the Back button)
• Use the up/down arrows to select a partition
• Use the tab key to highlight the Delete button and hit return
• Repeat until all partitions are deleted

Creating the Swap Partition

After all the partitions are deleted, we can start our RAID configuration. First, we are going to start with the swap memory partitions. Putting swap memory on a software RAID partition is not recommended. For this reason, simply create swap partitions on both hard disks.

• Tab to the New button and hit return
• Tab down to File System Type and select swap
• Tab to Allowable Drives and mark only hda and take the mark off of hdc.
• Tab down to Size (MB) and type in the size of your RAM in megabytes (MB)
• Tab down to OK and hit return.

Repeat the same process, but this time mark hdc as an allowable drive and take the mark off of hda.

Creating RAID Partitions

The boot partition (/boot) is where we are going to start with our RAID solution.

• Tab to the New button and hit return
• Tab down to File System Type and select software raid
• Tab to Allowable Drives and mark only hda and take the mark off of hdc.
• Tab down to Size (MB) and type in 100
• Tab down to OK and hit return.

Repeat the same process, but this time mark hdc as an allowable drive and take the mark off of hda. Now that we have two identical 100 MB partitions on both disks, we can create the software RAID disk:

• Tab to the RAID button and hit return
• Type in /boot in the Mount Point field
• Tab to RAID Level and select RAID1
• Tab to RAID Members and make sure the two partitions created earlier are selected

This example creates the /boot partition. Go through the same process for the root partition (/) and optionally any other partition that you want to create (/home, /var, etc.).

Configuring the Boot Loader

We are almost done with the software RAID configuration. Next, the installation wizard will ask for the boot loader settings.

• Select Grub as your boot loader
• Disable the boot password (unless you really need it)

	Warning!

If have trouble booting up your system with Grub, you can use the Lilo boot loader as an alternative. However, you will need to type the following on the first installation screen: linux lilo.

If the secondary disk fails (/dev/hdc), then the system will still be bootable. If the primary disk fails (/dev/hda), then your system will not boot. In order to make the secondary disk bootable as well, run the following command:

grub-install /dev/hdc

Or:

grub-install --recheck /dev/hdc

Testing Software RAID

If you would like to sanity check your RAID system, then:

• Power down the machine
• Unplug the data connector from the drive (just unplugging the power is going to make the BIOS unhappy and the system will not be bootable)
• Power up the machine

Links

• Software RAID Howto
• Old Red Hat Installation Guide