On 28 Nov, [EMAIL PROTECTED] wrote:
[clip]
> If the controller is built right, there is some potential for a performance
> increase. The idea is to have more than one drive simultaneously reading
> into it's buffer (they run about .5M these days). Assuming each drive stays
> busy, ie, as would be the case in large sequential transfers, it is possible
> to produce a rate at the host that approaches the combined rate of the
> drives. Same theory holds for SCSI, or Fibre Channel, for that matter.
[snip]
The problem with UDMA or any other IDE derivative is that only one
device can communicate on the bus at a time. In the case of a
master/slave situation, you're looking at no better than single-drive
performance (caps at about 20MB/s for really good drives). For a
controller with two channels, primary/secondary, you can get double
performance, in theory. So in theory you're looking at no better than
40MB/s with RAID-0. With UDMA somewhat more realistic numbers are
probably half that, as I understand it. Someone on here who has more
experience (I only use SCSI so I'm not an authority by any stretch of
the imagination), and I know there are plenty, can probably give you
better figures. I'm just regurgitating what I've seen time and time
again on this list in the past.
--
Jeremy Stanley, Network Engineer, Trend CMHS
"I program my homecomputer; beam myself
into the future." - Kraftwerk, 1981
