LSI 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 15
The initiator takes one ID per channel. This leaves 15 IDs
available for one channel.