Controller BIOS and BIOS Upgrades

Much the way that a PC motherboard has its system BIOS--low-level software that runs the chipset and other key components of the motherboard--hardware RAID controllers do too. The controller BIOS is the code that operates the controller, managing the RAID array.

Over time, the manufacturer of the RAID controller may change the BIOS code; this is usually done to correct minor problems with the controller card, but sometimes occurs to enable new features. It is also occasionally done to enable support for hardware that did not exist at the time the controller shipped. Like PC BIOSes, RAID controller card BIOSes can usually be upgraded through a flash process similar to that used for motherboards. A new BIOS is typically downloaded from the web site of the manufacturer and written to the EEPROM (flash chip) on the RAID controller. A special software program, called a flash program for unsurprising reasons, is used to ensure that the BIOS upgrade works properly.

Warning: To avoid potential problems, always follow the manufacturers' instructions carefully when attempting to flash any BIOS. Doing the flash procedure incorrectly can render the controller card inoperative. Always use the right BIOS image for your card, and make sure the data on the array has been backed up before you begin.

It's not necessarily a good idea to update the BIOS every time the manufacturer puts out new code. Check the release notes for the new version to find out what has changed; if no important changes have been made that affect how you will use the controller, you may not need to bother.

For software RAID there is no "controller BIOS", since the operating system is running the array. The analog for the controller BIOS upgrade here is the operating system patch, which most PC users know all too well. It's rare for problems with RAID in an operating system to occur that necessitate such a software patch, but it's still worth keeping current on whatever operating system you are using, since patches usually correct scores (or even hundreds) of bugs and problems.

Next: RAID Interfaces