Tip #4368 - RAID Hard Drives
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Q:
What is a RAID hard drive? I've been hearing about them quite a bit
lately, but I have no clue what they are or if I should really consider
using one. Please explain!
A:
Oh yes, this is a great question! Plus, it's
about another hard drive, so it goes along great with the quick tip
up above. The RAID frenzy actually goes back to the
1980s when three researchers from the University of California Berkeley
put together a case for "Redundant Arrays of Inexpensive Disks,"
which brought to life the acronym of RAID. And that's how it all began.
Keep reading to learn all about this unique discovery!
Basically, in
a RAID system, two or more inexpensive hard drives are put together
to create one single large capacity storage device that also offers
an enhanced performance. When the RAID system was first introduced,
it was mainly used by large businesses that needed a large amount
of data storage space. I mean, yes, it can protect you against data
loss if one of the hard drives fail, but it's not really meant to
be used as a backup solution for the average user. But, in the last
couple of years, RAID has increased in popularity and it's starting
to be used in more personal computer systems.
Now, RAID can
actually be classified into two different categories: hardware RAID
and software RAID. On the hardware side of things, the storage system
created by the two hard drives is managed separately from the host
computer, which then shows up as a single drive to the computer. The
host computer doesn't even really have to know that a RAID system
is being used. As far as hardware goes, some of the RAID systems are
put into place with a special hard drive controller card or the RAID
functionality can be built right into the motherboard.
On the other hand,
for the software side, the host computer handles everything. It's
what makes the RAID system look like one single hard drive. Unfortunately,
this method does decrease the overall performance of the RAID system
a little bit, because it functions by using some of the system's memory
and CPU cycles, which makes it completely dependent on the CPU.
With all of that
said, there are six different levels of RAID:
1.) RAID
0 - This level requires a minimum of two disks. It does provide
improved performance, but it doesn't account for data repetition or
failures. With this level, data striping is used so that the data
is all split up onto the two disks. So, yes, this method does work
at a very high level of performance, but if either of the drives fail,
all of that data will be lost for good. I guess there's always a price
to pay.
2.) RAID
1 - This level is a mirrored set of two disks in which the
data is replicated to separate hard disks in real time. It's done
that way to ensure continuous availability, currency and accuracy.
This level does provide fault tolerance in case any disk errors or
failures occur.
3.) RAID
3 and 4 - These two levels are combined together in a set
of three or more disks. One of those disks is mainly used for error
checking, so if that particular one fails, the other two will be able
to continue working without the error checking function. On the other
hand, if one of the data drives itself fails, all of the RAID data
will be lost.
4.) RAID
5 - This level is also a set of three or more disks, but
for this method, the error checking disk is split up between all three
drives. In that case, one single drive failure can be handled, but
if more than one drive fails, all of the RAID data will be lost.
5.) RAID
6 - This last level is a set of four disks (minimum) and
two of them are used for error checking only. With that being multiplied,
the RAID system can still operate if two of the other drives fail.
Once one of the drives is replaced, the data can still be saved and
it is then split up between all of the RAID drives.
Now, the level
of RAID you should use depends on what you do with your computer.
For example, if you do a lot of video processing or gaming, you're
going to want a more reliable RAID system, such as level 5 or 6. If
you do a lot of banking and online shopping with your computer, you
will want a safer RAID system, so the mirrored option of level 1 may
be your best bet. It all depends on your computing activities.
RAID systems are
available for Windows, Mac OS X and Linux operating systems. Now,
if you're interested in getting one for your computer, I would definitely
suggest looking into it a little more. You can certainly use this
tip as a reference, but you'll want to do some of your own researching
as well. RAID is an inexpensive way to go, but you have to make sure
it's going to work well enough for you and your computer. I must admit
though, it's a very interesting concept and if any of you use RAID
or plan to in the near future, I'd love to hear about it!
~ Erin
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