RAID
Redundant Array of Independent Disks is
a redundant system uses multiple Hard Drive to store your data,so if
one drive is fail your data is safe and accessible.
Mirroring – Multiple disk containing
identical data
Striping - sequential blocks of data
are split among multiple disk
Fault-tolerant – This is where
parity data is stored allowing data to be recovered if a problem is
detected
RAID 0
This configuration is the fastest of all the RAID levels, it uses a technique called data striping (see below) and requires at least 2 hard disks.
RAID
1
This level uses a pair of hard disks at a time to provide fault tolerance (there is no performance benefit) and requires at least 2 hard disks.
Using a technique called disk mirroring (see below) the same data is written to both disks at a time, so if one hard disk crashes then the same data is available from the remaining hard disk.
RAID
5
Data is striped across the drives in bytes, the parity data for one particular drive is stored on another drive allowing the data to be rebuilt using the parity technique.In the event of a disk failure, the data from the failed disk is reconstructed from parity striped across the remaining disks.
Minimum
number of drives required: 3
Usable capacity will be generally be
the physical capacity less one drive.
So if u have 4
1TB drives there only 3 TB of usable capacity
RAID
6 (double parity)
RAID
6 is similar to RAID 5 in terms of striping and parity, with the
major difference being that RAID 6 can tolerate two disk drives
failing.
Minimum
number of drives required: 4
Usable capacity will be generally be
the physical capacity less two drive.
So
if u have 4 1TB drives there only 2 TB of usable capacity
RAID
10
Initially a pair of drives is mirrored
as in RAID 1 and further striped as in RAID 0. Raid 10 is also known
as RAID 1+0 .
Minimum
number of drives required: 4
Usable capacity will be generally be
the physical capacity less two drive.
So
if u have 4 1TB drives there only 2 TB of usable capacity
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