Promise Technology VTrack M-Class M200i - Manual (Page 253)

Chapter 7: Technology Background
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RAID 50 – Striping of Distributed Parity
RAID 50 combines both RAID 5 and RAID 0 features. Data is striped across
disks as in RAID 0, and it uses distributed parity as in RAID 5. RAID 50 provides
data reliability, good overall performance and supports larger volume sizes.
Figure 5. RAID 50 Striping of Distributed Parity disk arrays
RAID 50 also provides high reliability because data is still available even if
multiple disk drives fail (one in each axle). The greater the number of axles, the
greater the number of disk drives that can fail without the RAID 50 array going
offline.
RAID 50 arrays consist of six or more physical drives.
Recommended applications: File and Application Servers, Transaction
Processing, Office applications with many users accessing small files.
RAID 50 Axles
When you create a RAID 50, you must specify the number of axles. An axle
refers to a single RAID 5 array that is striped with other RAID 5 arrays to make
RAID 50. An axle can have from three to eight physical drives, depending on the
number of physical drives in the array.
The chart below shows RAID 50 arrays with 6 to 15 disk drives, the available
number of axles, and the resulting distribution of disk drives on each axle. VTrak
Data
Stripes
Distributed Parity
Disk Drives
Axle 1
Axle 2