Voyager 3000 User Guide
RAID 3
Block Striping with Dedicated Parity - Data is broken into logical blocks, the size of a SCSI disk block, and striped across several drives. One drive is dedicated to parity. In the event of failure, original data is
Table 1-7 RAID 3 layout
Drive 0
A0
A4
B3
C2
Drive 1
A1
B0
B4
C3
Drive 2
A2
B1
C0
C4
Drive 3
A3
B2
C1
D0
Drive 4
P
P
P
P
RAID 5
Multiple Block Striping with Distributed Parity - Sets a given number of logical blocks as a unit for striping across several drives. For small read/write operations, one drive may be activated for improved small record access speed. In this case we can process multiple I/O requests simultaneously. Parity information is interleaved across the drive array. In the event of failure, original data is regenerated from the parity information.
Table 1-8 RAID 5 layout
Drive 0
Drive 1
p
Drive 2
P
Drive 3
P
Drive 4
P
Required Number of Drives and Net Capacity
The following table gives a summary of the minimum number of drives required and the capacity available for the different types of RAID operation:
Table 1-9 Minimum drives necessary for a RAID set
OPERATION | MIN. DRIVES | CAPACITY |
| REQUIRED | AVAILABLE |
RAID 0 | 2 | T |
RAID 1 | 2 | T / 2 |
RAID 0 + 1 | 4 | T / 2 |
RAID 3 | 3 | T x (n - 1) / n |
RAID 5 | 3 | T x (n - 1) / n |
T = Sum of the capacity of all connected drives n = Number of connected drives
