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7 RAID Management
This section describes the available RAID Management tasks; these tasks may be selected
from the RAID subsystem menu in the left tree node of the ProRAID Manager screen.
7.1 About RAID
RAID stands for Redundant Array of Independent Disks. A RAID system consists of two or
more disks in parallel. This array of disks appears as one disk drive to the host computer
offering enhanced performance or data reliability or both.
There are different RAID levels with each level being suited to a particular application. For
example, RAID Level 1 uses mirroring to hold your data in 2 separate but identical locations.
If a disk fails the RAID controller will use either the data disk(s) or the mirror disk(s) for data
recovery giving you constant access to your data. This RAID Level is particularly suited to
mission critical applications such as accounting systems.
7.1.1 RAID Considerations
7.1.1.1 How Many Disks Are Available?
The number of physical disks that are available will influence your decision about which RAID
level you can choose and whether or not you can have a spare drive(s). The following table
shows the minimum number of disks that are required to implement each RAID level.
RAID Level
Minimum Number of
Disks
JBOD 1
Linear 1
0 2
1 2
3 3
5 3
6 4
0 + 1
4
30 6
50 6
If you wish to have a Spare Drive, you will need to have at least the minimum number of
disks, plus a disk for every Spare Drive you require.
7.1.1.2 Spare Drive Strategy
A Spare Drive is a disk drive that is set aside when creating your RAID system so that it can
be used to rebuild a RAID in the event of a disk drive in that RAID failing. This reduces the
risk to your data as the RAID can be rebuilt immediately without installing a new disk to
replace a failed disk in the RAID.
