- Editorial: RAID time IDE style by Saeed Amen
are special. Hard disk are generally IDE devices or faster and more expensive
SCSI devices. Until a few years ago RAID card only supported SCSI drives.
However, more recently RAID IDE cards have come on to the market. But
what is RAID? It's quite simple. A RAID controller is usually a PCI card.
It connects to hard disks, and you have the option of running the drives
in different modes, RAID 0, 0+1, 1, or 5.
RAID 0, requires two identical hard drives (or an even number). When data
is read or written, the work is split between the drives. Consequently
data is read or written double (or even more) the speed. Consequently
you can buy two cheap IDE drives and get fantastic performance. The downside
of RAID 0 Stiped, is if one drive fails the whole array could fail. This
happened with me once. An error meant I couldn't start Windows to read
data. So I had to get another hard disk, install Windows, back-up as much
data as I could, and then format the RAID array. With RAID you have the
option of viewing the whole RAID array as one partition, but I wouldn't
recommend this! With RAID 1, you don't get extra performance. Data is
mirrored, so one drive is a copy of the other. This means if one fails,
it doesn't matter, since you still have the data on the other drive. RAID
0+1 uses four drives, so each drive is mirrored and you also get striping.
This is excellent, so you the extra speed, and it's also as reliable as
an ordinary hard disk setup. On more expensive RAID cards you also have
RAID 5, which is a combination of RAID 1 and 0. So it gives you a balance
of extra speed (but not as quick as RAID 0 or 0+1) and reliability.
Before it was just servers and high-end workstations that employed RAID,
now it's become cheaper and supports IDE, it's come to the masses. It's
only a matter of time, before computer manufacturers fit it as standard
to their more expensive machines.