Supported Disk Array Types - Promise Technology FASTTRAK66 User Manual

Manual EN 05-08-1999 11:30 Pagina 47
Understanding Disk Array Concepts

Supported Disk Array Types

Striping (RAID 0)
Reads and writes sectors of data interleaved
between multiple drives. When any disk mem-
ber fails, it affects the entire array.
Performance is better than a single drive since
the workload is balanced between the array
members. This array type is for high perfor-
mance systems. Identical drives are recom-
mended for performance as well as data stora-
ge efficiency. The disk array data capacity is
equal to the number of drive members times
the smallest member capacity. For example,
one 1GB and three 1.2GB drives will form a
4GB (4 x 1GB) disk array.
Stripe Size - a value can be set from 1KB to 1024KB sector size. The size can
directly affect performance. In the FastBuild BIOS, the "Desktop" default is
8KB while "Server" and "A/V Editing" are 64KB.
Mirroring (RAID 1)
Writes duplicate data on to a pair of drives
while reads are performed in parallel . IDE
RAID 1 is fault tolerant because each drive of
a mirrored pair is installed on separate con-
nectors - follow the "Drive Setup By
Connector" chart in Chapter 3.
FastTrak66 performs reads using advanced
data handling techniques that distribute the
workload in a more efficient manner than
using a single drive. When a read request is
made, FastTrak66 selects the drive positioned
closest to the requested data, then looks to the
"idle" drive to perform the next read access.
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