Raid Configuration Strategies - Lenovo ThinkServer RD650 User Manual

12Gb/s MegaRAID SAS Software User Guide
March 2014
Table 14 RAID 60 Overview
Uses
Strong points
Weak points
Drives
The following figure shows a RAID 60 data layout. The second set of parity drives is denoted by Q. The P drives follow
the RAID 5 parity scheme.
Figure 14 RAID 60 Level Virtual Drive
2.3

RAID Configuration Strategies

The following factors in RAID drive group configuration are most important:
Virtual drive availability (fault tolerance)

Virtual drive performance

Virtual drive capacity

You cannot configure a virtual drive that optimizes all three factors, but it is easy to choose a virtual drive
configuration that maximizes one factor at the expense of another factor. For example, RAID 1 (mirroring) provides
excellent fault tolerance, but requires a redundant drive.
The following subsections describe how to use the RAID levels to maximize virtual drive availability (fault tolerance),
virtual drive performance, and virtual drive capacity.
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 re-create 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.
Not well suited to tasks requiring lot of writes. A RAID 60 virtual drive has to generate two sets of parity data for
each write operation, which results in a significant decrease in performance during writes. Drive performance
is reduced during a drive rebuild. Environments with few processes do not perform as well because the RAID
overhead is not offset by the performance gains in handling simultaneous processes. RAID 6 costs more
because of the extra capacity required by using two parity blocks per stripe.
A minimum of 6.
LSI Corporation
- 35 -
Chapter 2: Introduction to RAID
RAID Configuration Strategies