Redundant Array of Independent Disks (RAID)


  • Arrays or Jukeboxes of CD-ROM’s or CD-R’s. There are five commonly used, different levels of data protection, RAID 1 through RAID 5, which are tradeoffs of protection versus storage capacity. These include:
    • Level 0: Data written in blocks across multiple drives without an protection on failures.
    • Level 1: Disk Mirroring.
    • Level 3: The drive spindles are synchronized such that the heads all seek at the same time and are positioned over the same read/write areas simultaneously. Data is written one bit at a time with parity to a separate drive. Thus if there were four disks in the array and there was a megabyte of data to transferred at 1 MB/sec, the effective rate is 4MB/sec.
    • Level 5: Writes data in chunks (usually smaller blocks 512 bytes to 2 K) with the parity striped along with the data. Achieves a higher I/O rate.



  1. Formerly American Document Management, Glossary of Terms, now 5i Solutions Glossary.