RAID

Revision as of 10:02, 13 August 2012

RAID is an acronym for Redundant Array of Inexpensive Disks, often found on servers, enables multiple hard-drives to be accessed by the system as though they were a single storage device. RAID devices or software can be configured in various ways to boost disk performance (faster reading and writing) and/or for fault-tolerance (so that if a physical disk fails, the failed disk can be replaced without loss of data; and pending replacement of the data will continue to be available).

There are many different types of RAID, with the most common variants being as follows:

RAID0 - striping without parity (added storage space, decreased reliability) - NOT recommended!
RAID1 - simple mirroring (added access speed and reliability, no change to storage space)
RAID3 - striping with a single parity provider (added storage space, added reliability)
RAID5 - striping with distributed parity across all providers (added storage space, added reliability)

FreeBSD offers solid and reliable kernel-level software RAID at the RAID0, RAID1, and RAID3 levels via the geom module. (Examples of installation and usage are present at many of the individual RAID level articles above.)

Geom RAID5 is available via patches, but has not been implemented in the base system yet - and many argue that RAID3, while not as commonly seen in the outside world, is actually a superior setup anyway. (Jimbo agrees with this statement.)