Managing RAID on Linux

Patching Older Kernels

Working with 2.0.X and 2.2.X kernels can be extremely confusing because of the layout and documentation for the available patches. Most people have a lot of trouble sifting through all the old and erroneous information relating to these kernel versions and their RAID implementations. While RAID support is included with 2.0.X and 2.2.X series kernels, the most recent drivers are not distributed with the kernel source code, and patches should be applied when possible. There are also known problems with RAID-5 on 2.2 and 2.0 kernels, so if you want to use RAID-5, you should upgrade to at least a 2.4 kernel.

Kernel 2.2

When working with 2.2 series kernels, I strongly recommend that you upgrade to the latest RAID code (0.90). The 0.90 code is available as a patch to the kernel and should be applied before any attempt to build new arrays. As a general principle, you should always be working with version 0.90 (or later) of the RAID code. You can examine the file .../linux/include/linux/md.h to determine which version of the RAID code is present on 2.0 and 2.2 series kernels. Version information is located near the beginning of the file:

[...]
#define MD_MAJOR_VERSION                0
#define MD_MINOR_VERSION                36
#define MD_PATCHLEVEL_VERSION           6
[...]

This 2.2 kernel has version 0.36.6 of the RAID subsystem; therefore, a patch should be applied. If .../linux/include/linux/md.h is either empty or missing, your kernel is probably already patched to version 0.90. Instead, check the file ...