1-6
Adaptec ATA RAID 1200A Installation and User’s Guide
■
RAID 1, Mirroring
—Data is mirrored on one pair of disks
providing 100 percent redundancy. Offers complete fault
tolerance. If one disk fails, data is still available. Increases read
performance through striping, but write performance is
unaffected. Adaptec recommends using the same size disks, but
if you use a disk with less disk space, the actual data capacity of
the array equals the smaller capacity disk.
■
RAID 0/1, Mirrored Striping
—Increases both read and write
performance. Data is striped and mirrored on two or more pairs
of disks. Offers complete fault tolerance. If one disk in a pair
fails, data is still available. The actual data capacity of the array
equals the available disk space of the smaller RAID 0 array.
■
JBOD, Volume
—Subsystem of disk drives. Allows you to
combine disk drives into larger logical volumes. Two or more
hard disk drives of unequal size can be grouped to appear as
one single device to the host system. Doesn’t provide fault
tolerance. Adaptec recommends using the same size disks, but
if you use a disk with less disk space, you can combine the disks
into a single unit without loss of any capacity.
RAID Performance Hints
The following suggestions provide the best performance and
reliability:
■
Use ATA 66/100 hard disks.
■
Use the same model hard disk drive throughout the system.
Different models exhibit different timing characteristics, which
might decrease overall RAID performance.
■
If you have only two hard disk drives, connect each on a
different channel as a master drive.
■
If you are using mirrored pairs, group each pair on a separate
connector.
■
Always use 80-conductor cables.
ATA RAID 1200A IUG.book Page 6 Wednesday, November 13, 2002 2:22 PM
