Lenovo ThinkServer RD240 MegaRAID SAS Software User Guide - Page 57

RAID 50 Level Virtual Drive, Table 2.11, RAID 50 Overview, RAID 50, Strong Points

Page 57 highlights

50 is best implemented on two RAID 5 drive groups with data striped across both drive groups. RAID 50 breaks up data into smaller blocks and then stripes the blocks of data to each RAID 5 disk set. RAID 5 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 level 50 can support up to eight spans and tolerate up to eight drive failures, though less than total drive capacity is available. Though multiple drive failures can be tolerated, only one drive failure can be tolerated in each RAID 5 level drive group. Table 2.11 provides an overview of RAID 50. Table 2.11 RAID 50 Overview Uses Strong Points Weak Points Drives Appropriate when used with data that requires high reliability, high request rates, high data transfer, and medium to large capacity. Provides high data throughput, data redundancy, and very good performance. Requires 2 to 8 times as many parity drives as RAID 5. Eight spans of RAID 5 drive groups containing 3-32 drives each (limited by the maximum number of devices supported by the controller) Figure 2.11 RAID 50 Level Virtual Drive RAID 50 Segment 1 Segment 2 (Segment 1,2) Segment 3 Segment 4 (Segment 3,4) Segment 6 (Segment 5,6) Segment 5 Segment 8 (Segment 7,8) Segment 7 (Segment 9,10) Segment 9 Segment 10 (Segment 11,12) Segment 11 Segment 12 RAID 5 RAID 0 RAID 5 RAID Levels 2-25

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RAID Levels
2-25
50 is best implemented on two RAID 5 drive groups with data striped
across both drive groups.
RAID 50 breaks up data into smaller blocks and then stripes the blocks
of data to each RAID 5 disk set. RAID 5 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 level 50 can support up to eight spans and tolerate up to eight
drive failures, though less than total drive capacity is available. Though
multiple drive failures can be tolerated, only one drive failure can be
tolerated in each RAID 5 level drive group.
Table 2.11
provides an overview of RAID 50.
Figure 2.11
RAID 50 Level Virtual Drive
Table 2.11
RAID 50 Overview
Uses
Appropriate when used with data that requires high
reliability, high request rates, high data transfer, and
medium to large capacity.
Strong Points
Provides high data throughput, data redundancy, and
very good performance.
Weak Points
Requires 2 to 8 times as many parity drives as RAID 5.
Drives
Eight spans of RAID 5 drive groups containing 3-32
drives each (limited by the maximum number of devices
supported by the controller)
Segment 1
Segment 2
Segment 5
Segment 6
RAID 0
RAID 50
(Segment 1,2)
Segment 3
Segment 4
Segment 8
Segment 7
Segment 9
Segment 10
Segment 11
Segment 12
(Segment 5,6)
(Segment 9,10)
(Segment 11,12)
(Segment 7,8)
(Segment 3,4)
RAID 5
RAID 5