Chapter 1. Introducing the 3ware® 9000 Series Controller
10 3ware Serial ATA RAID Controller User Guide
Drive Capacity Considerations
The capacity of each drive is limited to the capacity of the smallest drive in
the array. The total array capacity is defined as follows:
Table 3: Possible Configurations Based on # of Drives
# Drives Possible RAID Configurations
1 Single drive or hot spare
2 RAID 0 or RAID 1
3RAID 0
RAID 1 with hot spare
RAID 5
4 RAID 5 + hot spare
RAID 10
Combination of RAID 0, RAID 1, single disk
5 RAID 5 + hot spare
RAID 10 + hot spare
Combination of RAID 0, RAID 1, hot spare, for single disk
6 or more RAID 50
Depending on the number of drives, a RAID 50 may contain from
2 to 4 subunits. For example, with 12 drives, possible RAID 50
configurations include 2 subunits of 6, 3 subunits of 4, or 4
subunits of 3. With 10 drives, a RAID 50 will contain 2 subunits of
5 drives each. With 16 drives, a RAID 50 will contain 2 subunits
of 8 drives or 4 subunits of 4 drives.
Combination of RAID 0, 1, 5, 10, hot spare, and single disk
Table 4: Drive Capacity
RAID Level Capacity
RAID 0 (number of drives) X (capacity of the smallest drive)
RAID 1 capacity of the smallest drive
RAID 5 (number of drives - 1) X (capacity of the smallest drive)
Storage efficiency increases with the number of disks:
storage efficiency = (number of drives -1)/(number of drives)
RAID 10 (number of drives / 2) X (capacity of smallest drive)
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