Managing RAID on Linux

Summary of Kernel Upgrades

In summary, the latest version of the software RAID (multiple devices) driver for Linux is 0.90. However, kernels 2.0 and 2.2 were distributed with an older version (0.36) of the driver. If you are using kernel 2.4 or later, then you already have the latest driver, but you might wish to check the web pages of both Ingo Molnar (http://people.redhat.com/mingo/raid-patches/) and Neil Brown (http://www.cse.unsw.edu.au/~neilb/patches/linux-stable/) for performance and reliability patches that are waiting to make it into the next kernel revision.

When working with 2.0 and 2.2 kernels, it’s essential to upgrade to the 0.90 driver whenever possible. Follow the steps described in this section to download the appropriate patch and apply it to your kernel. If you encounter problems during this process, you might need to try patching different kernel sublevel releases until you find one that patches without errors. Use kernels that do not patch properly at your own risk.

If, for one reason or another, you are working with a 2.0 or 2.2 kernel and cannot upgrade to the 0.90 RAID, than you are in the unfortunate circumstance of having to use the very outdated 0.36 driver. The 0.36 driver is not compatible with the newer 0.90 driver, and you will need to use an older version of the raidtools package to manage arrays created for the 0.36 driver. Only four software arrays are supported under version 0.36.