Raid 00 - Lenovo ThinkServer RD650 User Manual

12Gb/s MegaRAID SAS Software User Guide
March 2014
Table 10 RAID 6 Overview
Uses
Strong points
Weak points
Drives
The following figure shows a RAID 6 data layout. The second set of parity drives is denoted by Q. The P drives follow
the RAID 5 parity scheme.
Figure 10 Example of Distributed Parity across Two Blocks in a Stripe (RAID 6)
2.2.7

RAID 00

A RAID 00 drive group is a spanned drive group that creates a striped set from a series of RAID 0 drive groups. RAID 00
does not provide any data redundancy, but, along with RAID 0, does offer the best performance of any RAID level.
RAID 00 breaks up data into smaller segments and then stripes the data segments across each drive in the drive
groups. The size of each data segment is determined by the stripe size. RAID 00 offers high bandwidth.
By breaking up a large file into smaller segments, the controller can use both SAS drives and SATA drives to read or
write the file faster. RAID 00 involves no parity calculations to complicate the write operation. This situation makes
RAID 00 ideal for applications that require high bandwidth but do not require fault tolerance. The following table
provides an overview of RAID 00. The following figure provides a graphic example of a RAID 00 drive group.
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. 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 5.
Not well-suited to tasks requiring a lot of writes. A RAID 6 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.
3 through 32.
NOTE RAID level 00 is not fault tolerant. If a drive in a RAID 0 drive group fails,
the entire virtual drive (all drives associated with the virtual drive) fails.
LSI Corporation
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Chapter 2: Introduction to RAID
RAID Levels