Promise Technology VTrak 15110 - Manual (Page 219)

Chapter 7: Technology Background
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RAID 5 – Block Striping with Distributed Parity
RAID 5 is similar to RAID 3 as described above except that the parity data is
distributed across the disk drives along with the data blocks. In each case, the
parity data is stored on a different disk than its corresponding data block.
RAID 5 makes efficient use of hard drives and is the most versatile RAID Level. It
works well for file, database, application and web servers.
Figure 4. RAID 5 Stripes all drives with data and parity information
The capacity of a RAID 5 disk array is the smallest disk drive size multiplied by
the number of disk drives, less one. Hence, a RAID 5 disk array with four 100 GB
disk drives will have a capacity of 300 GB. A disk array with two 120 GB disk
drives and one 100 GB disk drive will have a capacity of 200 GB.
RAID 5 disk arrays on VTrak consist of 3 to 15 disk drives.
Data
Blocks
Distributed Parity
Disk Drives