RAID: Kills Bugs Dead :-)
If you want blazing speed and have the money to burn then
get a RAID system. RAID stands for Redundant Array of Independent Disks.
Basically, it is multiple hard drives configured together to provide fault
tolerance, performance boosts or both. All the drives have to be the same
physical size.
There is software RAID and hardware RAID. Software RAID is
slower than hardware RAID by about 20% to 30%. Both NT and Linux support
software RAID. The benefits of software RAID is that no RAID controller is
needed. Hardware RAID uses a separate RAID controller for the hard drives. It
can be used in
any operating system that the controller has drivers for. They start at a price
of $360 and up. The more expensive ones have an onboard RAM cache which varies
from 16MB and up.
Here are the most common RAID configurations:
RAID 0 Requires at least 2 Hard drives. This is known as disk striping
without parity. This combines the read/write head of the drives to act as one
large drive. So if you had two 9GB SCSI drives, they would be one 18GB drive
assigned to one drive letter. Works similar to 3DFX's SLI technology. But you
can pair up as many drives as your SCSI/RAID controller supports. Except an
increase of 65% (software based) to 90% (hardware based) in performance over a
single drive. However, this does not provide fault tolerance which means if any
of the drives fail, kiss your data good-bye.
RAID 1 Requires 2 Hard drives. This is known as Disk Mirroring. Disk 2 is an
exact copy of Disk 1. So if any of the disks fails, you keep on going. This
works good for mission critical applications. However, this does not increase
performance.
RAID 0/1 This is a combination of RAID 0 and 1. Requires at least four hard
drives. The first 2 drives are configured RAID 0, and the second two drives are
a copy of the first 2 drives. If 1 drives fails, you still keep on going.
Performance is increased over just a regular mirror, but still not as fast as
RAID 0. Note: RAID 0/1 cannot be done in software RAID without third party
programs
RAID 5 Known as Disk Striping with Parity. Similar to RAID 0 except provides
Fault Tolerance. All drives would be 1 big drive assigned 1 drive letter.
Requires 3 hard drives. 25% of each drive stores parity information of each
drive. If any of the drive fails, you simply replace the drive and rebuild the
parity. Increases Read performance similar to RAID 0, but Write performance is
not as increased because the operating system has to write the parity
information anytime its writing. Note: By default RAID 5 works with NT Server
and Linux only, not supported by NT Workstation.
Hardware RAID configuration is configured the same way as with a regular SCSI
controller and follows the same rules of termination.
Here's a picture of a RAID controller. This one is an AMI MegaRAID series 466
with 64MB of ECC EDO RAM
Notice, the Intel i960 CPU.
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