American Megatrends MegaRAID Express 500 - Manual (Page 39)

Chapter 3 RAID Levels 25
RAID 30
RAID 30 is a combination of RAID 0 and RAID 3. RAID 30 provides high data
transfer speeds and high data reliability. RAID 30 is best implemented on two
RAID 3 disk arrays with data striped across both disk arrays. RAID 30 breaks up
data into smaller blocks, and then stripes the blocks of data to each RAID 3 raid
set. RAID 3 breaks up data into smaller blocks, calculates parity by performing
an exclusive-or on the blocks, and then writes the blocks to all but one drive in
the array. The parity data created during the exclusive-or is then written to the
last drive in each RAID 3 array. The size of each block is determined by the
stripe size parameter, which is set during the creation of the RAID set.
RAID 30 can sustain one to four drive failures while maintaining data integrity if
each failed disk is in a different RAID 3 array.
Uses Use RAID 30 for sequentially written and read data, pre-
press and video on demand that requires a higher degree of
fault tolerance and medium to large capacity.
Strong Points Provides data reliability and high data transfer rates.
Weak Points Requires 2 – 4 times as many parity drives as RAID 3.
Drives Six to 32