Bill Vermillion
Guest
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 Posted:
Sat Nov 12, 2005 10:25 pm Post subject:
Re: Question to the Experts about Processors |
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In article <CqHbf.33404$NJ.7344@bignews7.bellsouth.net>,
Harvey <here@there.com> wrote:
| Quote: | No this is not exactly correct.
Raid 0 consists of 2 hard drives which are 'mirrored'.
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No. RAID 1 is a 'mirrored' configuration - where both disks have the
same data for safety. The lost of 1 drive just means you have lost
your safety net.
RAID 0 is 'stripped' where the data is split between the drives so
the loss of one drive means the loss of all data.
| Quote: | This means that the *same* information is written to both drives
at the same drive. If one breaks, the other can carry on until
the broken one is replaced. Then the mirror is 'rebuilt'.
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That is RAID 1. In RAID 0 you lose your data.
| Quote: | Raid 0 will generally be slower than a stand alone drive. However
there are many variables here. If each drive is on its own
controller, speeds will approach that of a dedicated drive, but
will never be faster than a single drive of similar type.
Raid 5 consists of a minimum of 3 drives. In this configuration,
2 drives will be 'striped'. Part of a file will be written to
one drive, part to the other. The third drive is used for error
correction. If one drive failes, the other two drives are able to
recreate the data.
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Actually in a proper RAID 5 the parity bits are rotated through the
drive array.
| Quote: | Raid 5 can be faster than either Raid 0 or standalone. Again,
it depends on the controllers and how it is setup. Dedicated
controller for each drive is fastest. Software controlled Raid is
slowest.
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In most cases RAID 5 is the slowest when it comes to writing - you
have a 50% more write overhead when you use three drives. And
a 3-drive RAID 5 is the lowest configuration while you can have
many more drives than three.
| Quote: | No clear cut answer. Raid is more about data redundency than
speed, though Raid 5 is sometimes used for speed as well.
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RAID 0 is speed with NO safety net at all.
RAID 1 is fastest.
RAID 5 means you can add many drives so your array can exceed the
size of any standard disk drives.
I used to run RAID in old Unix servers - most of the time it was
to get more data capacity. 200MB drives were only $400 each -
while a 600MB drive started at more than what the 3 smaller drives
cost.
Bill
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Bill Vermillion - bv @ wjv . com |
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