Smart Array 5300 Controller User Guide

Drive Arrays and Fault Tolerance
D-8 Compaq Smart Array 5300 Controller User Guide
COMPAQ CONFIDENTIAL
Writer: John Turner File Name: n-appd drive arrays and fault tolerance.doc
Codename: SilverHammer Part Number: 135606-004 Last Saved On: 7/22/02 11:02 AM
S1
S2
S3
S4
B1
B3
P5,6
P3,4
P1,2
P7,8
B7
B2
B5
B8
B4
B6
Figure D-7: Distributed data guarding, showing parity
information (Px,y)
Advantages
• High read performance
• No loss of data if one physical drive fails
• More drive capacity usable than with RAID 1+0—parity information requires
only the storage space equivalent to one physical drive
Disadvantages
• Relatively low write performance
• Loss of data if a second drive fails before data from the first failed drive is rebuilt