Promise Technology FastTrak66 Anwenderhandbuch Seite 68

Manual EN 05-08-1999 11:30
Appendix
RAID 0 (stripe)
For capacity -- The FastTrak/66 array will be as big as the smallest HDD in
the array times however many HDDs are in the array. Any larger HDDs will
simply be truncated. The truncated space on the bigger HDDs will then be
unusable.
For sustained data transfers -- Using FastTrak/66, a RAID 0 array consisting
of two HDDs will transfer at about twice the speed of the slowest HDD in the
array. A RAID 0 array consisting of four HDDs will transfer at about three
times the speed of the slowest HDD in the array.
RAID 1 (mirror)
For capacity -- The FastTrak/66 array will be as big as the smallest HDD in
the array. The larger HDD will simply be truncated. The truncated space on
the bigger HDD will then be unusable.
For sustained data transfers -- The FastTrak/66 array will write data at the
rate of the slowest HDD in the array. The FastTrak/66 array will read data at
twice the rate of the slowest HDD in the array.
JBOD (spanning)
For capacity -- The FastTrak/66 array will combine the sizes of the HDDs in
the array. As soon as one HDD is filled to capacity, the next HDD will auto-
matically be used.
For sustained data transfers -- There is no performance increase with
spanning (reading or writing).
Drive Issues
Q: Can I add a drive to a FastTrak66 RAID array via hot-swap and
dynamically adjust the array size/configuration?
A: No. The FastTrak66 system does not support dynamically adjustable RAID
size/configurations.
Q: Do the HDDs on the FastTrak/66 have to be the same size?
A: The HDDs that you use with the FastTrak/66 do not have to be the same
size. If the sizes differ, the FastTrak/66 will "adjust" the HDDs so that they
are compatible. Basically, it will truncate the bigger HDD so the sizes
match. Any unused space that results from this is unusable, so don't use
HDDs that differ too much. It'll work, but it's a waste.
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