Managing RAID on Linux

Preparing Controllers and Disks

It’s vitally important that all disks used in any hardware array are identical (see the Matched drives section in Chapter 2) and that all have the same firmware revision. There are documented cases in which non-uniform firmware revisions have led to data corruption. Furthermore, it’s important to use the latest firmware revision for both controllers and disks and, in some cases, even for the BIOS on your motherboard. In general, it’s a good idea to upgrade all system components to the most up-to-date firmware before placing any system in production.

Computer equipment, especially disk controllers and hard disks, tends to sit in warehouses for several months before it is shipped to resellers and end users. That usually means that by the time you purchase your equipment, there has been at least one firmware, or controller BIOS, release correcting important bugs that often affect interoperability or performance.

For example, a controller I was working with during the course of this writing wouldn’t work consistently using recently purchased SCSI hard disks that were a couple of firmware revisions behind. Hard disks often ship with older firmware, and that doesn’t usually affect systems that use standalone disks. However, since hard disk firmware controls environmental factors such as rotation speed and thermal calibration, using disks with varying firmware in an array can be catastrophic. To function optimally, RAID controllers require that all disks be ...