Promise Technology SMARTSTOR NS4300N - Manual (Page 166)

SmartStor NS4300N Product Manual
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RAID 5 – Block Striping with Distributed Parity
RAID 5 organizes block data and parity data across the disk drives. Generally,
RAID level 5 tends to exhibit lower random write performance due to the heavy
workload of parity recalculation for each I/O. RAID 5 works well for file, database,
application and web servers.
Figure 3. RAID 5 Stripes all drives with data and parity information
The capacity of a RAID 5 Volume equals the smallest disk drive times the
number of disk drives, minus one. Hence, a RAID 5 Volume with four 100 GB
disk drives will have a capacity of 300 GB. A RAID Volume with two 120 GB disk
drives and one 100 GB disk drive will have a capacity of 200 GB.
RAID 5 is generally considered to be the most versatile RAID level.
RAID 5 requires a minimum of three disk drives.
Data
Blocks
Distributed Parity
disk drives