Home | Contents | Help   Raidhelp     Defining RAID Level 4 RAID Level 4 is essentially RAID Level 3 with independent access instead of parallel access. It therefore provides high transaction rate performance instead of high transfer rates. RAID Level 4 is seldom implemented because the one or more disk drives dedicated to redundant information form a relatively severe write bottleneck. Level 4 therefore is dedicated to offering fault tolerance to data only and offers no performance advantages or architectural advantages over RAID Level 5. RAID 4 has a very low ratio of ECC disks to data disks and therefore offer high efficiency with a high aggregate Read transfer rate. The controller design however is fairly complex and carries an added penalty of offering the worst Write transaction rate and Write aggregate transfer rate. It is also difficult and inefficient on a rebuild in the event of disk failure. The Block Read transfer rate is equal to that of a single drive. Next: Level 5 Related topics: Defining RAID Levels Understanding Parity   Raidhelp   RAIDhelp© Copyright 1999-2004 Antony Kershaw