Since the subject of scsi and drive speed in general have come up in the last
couple of days I offer this information.
EIDE, Fast-ATA and ATA-2
These 3 terms are roughly equivalent, fast-ATA is ATA-2 but EIDE additionally
includes ATAPI. ATA-2 is what most use these days which is faster and with
DMA. Highest transfer rate is increased to 16.6 MB/s.
Ultra-ATA
A faster DMA mode that is approximately twice the speed of EIDE PIO-Mode 4
(33 MB/s). Disks with and without Ultra-ATA can be mixed on the same cable
without speed penalty for the faster adapters. The Ultra-ATA interface is
electrically identical with the normal Fast-ATA interface, including the
maximum cable length.
The ATA/66 was superceeded by ATA/100 and then ATA/133. While the interface
speed has improved dramatically the disks are often limited by
platter-to-cache limits which today stands at about 40 MB/s.
For more information read up on these overviews and whitepapers from Maxtor:
Fast Drives Technology on the ATA/133 interface and Big Drives Technology on
breaking the 137 GB limit.
Serial-ATA
A new, standard has been agreed upon, the Serial-ATA interface, backed by the
The Serial ATA group who made the announcement in August 2001.
Advantages are numerous: simple, thin connectors rather than old cumbersome
cable mats that also obstructed air flow, higher speeds (about 150 MB/s) and
backward compatibility.
More recent serial ATA systems now support 300 MB/s.
SCSI
SCSI has been improving steadily and here's a table showing it's speed.
Bus Speed (MHz) | 8 16 |Note
--------------------------------------------------
5 | 5 10 | Old
10 | 10 20 | Fast
20 | 20 40 | Fast-20 / Ultra
40 | 40 80 | Ultra 2
40 DDR | 80 160 | Ultra 3 / Ultra-160
80 DDR | 160 320 | Ultra-320
--Steve Szmidt
"For evil to triumph all that is needed is for good men to do nothing. Edmund Burke ----------------------------------------------------------------------- This list is provided as an unmoderated internet service by Networked Knowledge Systems (NKS). Views and opinions expressed in messages posted are those of the author and do not necessarily reflect the official policy or position of NKS or any of its employees.
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