An Overview of RAID Chris Erickson Graduate Student Department of Electrical and Computer Engineering Auburn University, Auburn, AL 36849 [email protected] Objectives Raid definition Why RAID technology was invented RAID structure Current RAID applications What is RAID? Redundant Array Inexpensive / Independent Disks How does is work? Requires 2 or more hard drives Requires either hardware or software controller logic Allows disk drive storage to increase speed, reliability, or both at a minimal overhead cost Why RAID? Industries and companies require massive amounts of data to be securely stored. Tape storage is still prevalent for long term, archival storage but not effective for random access. Hard Disk Drives are perfect for random access in the Giga, Tera, Petabyte range. More RAID background Hard Disk Drives have a mean-time-to-error With the possibility of error, regardless of how small, something had to be done. Hard Disk Drives have a latency involved with seeking. For a PC the latency is almost negligible. When thousands of people are trying to access the same location, something had to be done RAID 0 Striped Delivers very high performance Requires 2 or more disk drives Data RAID 1 Mirroring Delivers the exact same data to 2 disks. Used for max redundancy and reliability. Data RAID 5 Stripe & Parity Provides the speed of striping and provides the parity for redundancy Data RAID 10 Provides dual RAID 1 configurations with RAID 0 mirroring Delivers the exact same data to 2 disks. Used for max redundancy and reliability. RAID 0 RAID 1 RAID 1 RAID The more drives the better the benefits RAID 5 is most popular for home & small office users. It provides the most inexpensive solution to have speed and reasonable reliability RAID 10 – Used by large corporations for maximum redundancy and reasonable speed Completed !! Any Question? Comments?