New Advanced RAID Level for Today's Larger Storage Capacities: Advanced Data Guarding
New Advanced RAID Level for Today's Larger Storage Capacities: 4
13JE-1000A-WWEN
RAID ADG provides greater fault tolerance
With growing numbers of individual disk drives needed in a single logical volume on a single
controller, RAID ADG provides higher data reliability than previously available from a RAID
storage provider. In Figure 1 below, RAID ADG has a superior fault tolerance when compared to
RAID 5 or RAID 1.
Figure 1 shows the probability of logical drive failure for various RAID levels and different
physical drive counts:
• With RAID 0, the logical drive will fail if one physical drive fails.
• With RAID 5, the logical drive will fail if two physical drives fail.
• With RAID 1 or 0+1, the maximum number of hard drives that can fail without failure of
the logical dive is n/2. However, a RAID 0+1 logical drive will fail if only two hard drives
fail, if they are mirrored to each other.
• With RAID ADG, three hard drives must fail before data loss is incurred.
Figure 1. RAID ADG Fault Tolerance Comparison
1 6 11 16 21 26 31 36 41 46 51 56
Total number of physical drives
Probability of Data Loss
Due to Second Hard Disk Drive Failure e
RAID ADG
RAID 0
RAID 1
RAID 5
0.00000000001%
1%