easyRAID E6, User Manual

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Introduction
When RAID Level 5 technology is combined with cache memory to
improve its write performance, the result can be used in any
applications where general purpose disks would be suitable.
For read only or read mostly application I/O loads, RAID Level 5
performance should approximate that of a RAID Level 0 array. In
fact, for a given user capacity, RAID Level 5 read performance
should normally be slightly better because requests are spread
across one more members than they would be in a RAID Level 0
array of equivalent usable capacity.
A RAID level 5 array performs best in applications where data and
I/O load characteristics match their capabilities :
Data whose enhanced availability is worth protecting, but for
which the value of full disk mirroring is questionable.
High read request rates.
Small percentage of writes in I/O load.
RAID Level 5 :
" Independent Access Array with Rotating Parity
"
High Data Reliability & Transfer Capacity
Disk 1 Disk 2 Disk 3 Disk 4 Disk 5 Disk 6
Physical
1
6
11
2
7
12
3
8
13
4
9
P
5
P
14
P
10
15
Data
1
2
3
4
5
6
7 8
9
10
11
12
Disk Array Controller
Array Management Software
Provides Logical to Physical Mapping
P : Parity
1-10