Managing RAID on Linux

RAID Autoconfiguration

Many RAID controllers come with automatic configuration features. These features are designed to make it easy for users who have no background in RAID to help determine which RAID level best meets their needs. I hope that, having purchased this book, you never need to use these features. Instead, configure your arrays manually, using the material from earlier chapters as a reference.

Autoconfiguration works by asking the user a series of questions that are used to determine performance and redundancy requirements. For example, the controller might prompt the user with the question:

Do you need fault tolerance?

Depending on whether the user answers yes or no, the controller can determine which RAID levels to eliminate from the possible choices. An answer of “no” eliminates RAID-1 and RAID-5, while answering “yes” includes them, but excludes RAID-0 and JBOD. A follow-up question might look like this:

Do you need a spare disk?

Depending on how this question is answered, the controller could determine how to size a potential array, based on the number of disks connected to the system.

Vendors have several different names for the autoconfiguration process, such as Auto Configure, Assisted Configuration, or Configuration Wizard, depending on the controller you purchase. I recommend against using these shortcuts, because they obfuscate the configuration process and build arrays using the lowest common denominator for important array properties. These features also don’t ...