Product manual

Galaxy G3G12 / G3G16 - Installation and Hardware Reference Manual
221 Section 7 Technology Background
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.
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.
Using a Galaxy3G subsystem expanded by four JBOD subsystems, your RAID 50 array supports up to 60
physical drives. See “Configuring JBOD Expansion” in chapter 2. However, we recommend that you set
aside a few physical drives as hot spares.
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 3 to 16 physical drives,
depending on the number of physical drives in the array.
Data
Stripes
Distributed Parity
Disk Drives
Axle 1
Axle 2
Fig 7.1e Striped sets of RAID 5