Lenovo ThinkServer RD240 Software User's Manual page 58

2.5.10 RAID 60
2-26
RAID 60 provides the features of both RAID 0 and RAID 6, and includes
both parity and disk striping across multiple drive groups. RAID 6
supports two independent parity blocks per stripe. A RAID 60 virtual
drive can survive the loss of two drives in each of the RAID 6 sets
without losing data. RAID 60 is best implemented on two RAID 6 drive
groups with data striped across both drive groups.
RAID 60 breaks up data into smaller blocks, and then stripes the blocks
of data to each RAID 6 disk set. RAID 6 breaks up data into smaller
blocks, calculates parity by performing an exclusive-or on the blocks and
then writes the blocks of data and parity to each drive in the drive group.
The size of each block is determined by the stripe size parameter, which
is set during the creation of the RAID set.
RAID 60 can support up to 8 spans and tolerate up to 16 drive failures,
though less than total drive capacity is available. Two drive failures can
be tolerated in each RAID 6 level drive group.
Table 2.12 RAID 60 Overview
Uses
Strong Points
Introduction to RAID
Provides a high level of data protection through the use
of a second parity block in each stripe. Use RAID 60 for
data that requires a very high level of protection from
loss.
In the case of a failure of one drive or two drives in a
RAID set in a virtual drive, the RAID controller uses the
parity blocks to recreate all of the missing information.
If two drives in a RAID 6 set in a RAID 60 virtual drive
fail, two drive rebuilds are required, one for each drive.
These rebuilds can occur at the same time.
Use for office automation and online customer service
that requires fault tolerance. Use for any application that
has high read request rates but low write request rates.
Provides data redundancy, high read rates, and good
performance in most environments. Each RAID 6 set
can survive the loss of two drives or the loss of a drive
while another drive is being rebuilt. Provides the highest
level of protection against drive failures of all of the
RAID levels. Read performance is similar to that of
RAID 50, though random reads in RAID 60 might be
slightly faster because data is spread across at least
one more disk in each RAID 6 set.