Promise Technology FAST TRAK100TM - Manual (Page 70)

FastTrak100 User Manual
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Disk Array Terms
Disk Array Description
A “disk array” is formed from a group of 2 or more disk drives which appear to the
system as a single drive. The advantage of an array is to provide better throughput
performance and/or data fault tolerance. Better performance is accomplished by
sharing the workload in parallel among multiple physical drives. Fault tolerance is
achieved through data redundant operation where if one (or more) drive fails or has
a sector failure, a mirrored copy of the data can be found on another drive(s).
For optimal results, select identical Ultra ATA/100 drives to install in disk arrays.
The drives’ matched performance allows the array to function better as a single
drive.
Disk Array Member
The individual disk drives in an array are called “members.” Each member of a
specific disk array is coded in their “reserved sector” with configuration information
that identifies the drive as a member. All disk members in a formed disk array are
recognized as a single physical drive to the system.
Disk Array Types
For most installations, the FastBuild T M setup “<1> Auto Setup” option will
configure your system.
There are four disk array types in three categories that can be installed on the
FastTrak100 card. Striping is in the Performance category while Mirroring,
Striping/Mirroring are in the Fault Tolerance category. Spanning (JBOD) is in the
Capacity category.
Disk arrays within the Performance and Fault Tolerance categories conform with
the Redundant Array of Independent Disks technology, or RAID. The RAID levels
supported are 0, 1, and 0+1.
RAID Level
Performance Capacity
# of
Drives
RAID 0 (Striping)
RAID 1 (Mirroring)
RAID 0+1 (Stripe/Mirror)
JBOD (Spanning) Highest
Normal
High
Normal
# Drives x Smallest Size
50% min
50% min
100% of All Drives
2 to 4
2
4
2 to 4