Lenovo ThinkServer TS430 User Manual

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MegaRAID SAS Software User GuideChapter 2: Introduction to RAID
| Components and Features
Disk mirroring provides 100 percent redundancy, but is expensive because each drive
in the system must be duplicated. Figure4 shows an example of disk mirroring.
Figure 4: Example of Disk Mirroring (RAID 1)
2.4.10 Parity Parity generates a set of redundancy data from two or more parent data sets. The
redundancy data can be used to reconstruct one of the parent data sets in the event of
a drive failure. Parity data does not fully duplicate the parent data sets, but parity
generation can slow the write process. In RAID, this method is applied to entire drives
or stripes across all of the drives in a drive group. The types of parity are described in
Table2.
RAID 5 combines distributed parity with disk striping. If a single drive fails, it can be
rebuilt from the parity and the data on the remaining drives. An example of a RAID 5
drive group is shown in Figure5. RAID 5 uses parity to provide redundancy for one
drive failure without duplicating the contents of entire drives. RAID 6 uses distributed
parity and disk striping, also, but adds a second set of parity data so that it can survive
up to two drive failures.
Figure 5: Example of Distributed Parity (RAID 5)
Segment 1
Segment 2
Segment 3
Segment 1 Duplicated
Segment 2 Duplicated
Segment 3 Duplicated
Segment 4 Segment 4 Duplicated
Table 2: Types of Parity
Parity Type Description
Dedicated The parity data on two or more drives is stored on an additional disk.
Distributed The parity data is distributed across more than one drive in the system.
Segment 1
Segment 7
Segment 2
Segment 8
Segment 3
Segment 9
Segment 4
Segment 10
Segment 5
Parity (6-10)
Parity (11–15)
Parity (1-5)
Segment 6
Note: Parity is distributed across all drives in the drive group.
Segment 12
Segment 15
Segment 11
Segment 14
Segment 13
Segment 19
Segment 25
Segment 20
Segment 23
Segment 18
Segment 21
Segment 16
Segment 22
Segment 17
Parity (21-25)
Parity (26–30)
Parity (16-20)
Segment 24
Segment 30
Segment 27 Segment 29
Segment 26
Segment 28

Lenovo ThinkServer TS430 Specifications

General

Brand	Lenovo
Model	ThinkServer TS430
Category	Server
Language	English