RAID LEVELS EXPLAINED
RAID stands for
a redundant array of independent disks and used to be called redundant array of
inexpensive
There are many kinds
of different raid levels and the more common raid levels explained below:
Raid 0
Raid 0 is also
known as striping.
It stripes all
the data across all the disks when the write is performed.
There is no
redundancy because it's just making a stripe.
There are no
backups.
If there’s lose
in one disk, then it's gonna lose the data on that disk which is tied to the
data on the other disk, and therefore all the data is lost.
A minimum of 2
disks are required to have a raid 0 set.
The maximum number of disks depends on RAID controller or raid software based on how many it could handle.
It has high read and writes performance.
Raid 1
Raid 1 also called
mirroring.
It does offer
redundancy and protection of data.
Every time a
write is done it's written to both drives at the same time.
If there’s lose
in one disk, it has the exact copy of your data since it's a mirror it's an exact
copy in each.
But if data is
lost in both then it’s gonna lose all the data.
The solution is
to put data in a new disk, so the mirror set will rebuild itself.
A minimum of two disks is required because of mirroring.
It has high read and writes performance.
Raid 5
Also called striping
with parity.
It stripes all the
data to the disk for performance enhancements.
It also offers
redundancy and protection.
A minimum of 3
disks is required.
It uses parity
blocks also for data protection. So when it writes to one it's writing the
data to all
If there’s a
lose in one disk, it will not affect other disks because data could be put
on a new one.
It usually has
a hot spare.
Hot spare is used to rebuild all the information that was
lost off.
It does have slower
write performance because it has to write every disk and do the parity.
But it does have a fast read performance.
Raid 6
This level is
almost similar to raid 5
There’s an
addition of a parity bit.
The data will
not be lost even if two disk fails.
Raid 01
Also called a
mirror of stripes.
The data is
striped within each group for the performance.
Groups are
mirrored with each other.
It offers redundancy
and protection.
A minimum of 4 disk
is required.
Lose 50% of total
capacity.
Data will not
be lost if any one disk per set failed.
Decent write and higher read performance because of multiple
disks.
Raid 10
Also called stripe
of mirrors.
Have groups
that are mirrored so this is mirrored like a normal raid 1.
In this level,
data is striped across the raid.
A minimum of 4
disk is required, so it can have a mirror in both sides and then stripe it.
It also offers redundancy
and protection.
It loses 50% of capacity.
High read performance
because of striping in the multiple discs.
Decent write
performance because this got a right to multiple disks.
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