Difference between IDE and SCSI ??

[Les Mikesell]

Ben Kamen wrote:

> In the beginning, SCSI was always faster than IDE because the 
> intelligence of the drives (remember, IDE tends to be dumb as it's 
> controlled by the host), that lent the drives to be more expensive. So 
> think "server" and thus smarter, more expensive also demanded "faster".

Scsi needs less intervention by the main CPU but that doesn't 
necessarily translate to 'faster'.  The overall time is going to be 
limited by the seek and transfer rate of the drive itself, which is 
often identical between IDE and Scsi models.  The tradeoff in cost of 
putting intelligence on peripheral devices and the value of those extra 
main CPU cycles (often spent waiting idly in is single-user computer 
anyway) has bounced back and forth over the years.  In a file server 
with lots of drives, scsi is usually a big win compared to typical ide 
controllers because it lets all the disks seek independently at the same 
time.  However even that isn't quite so simple, since specialized 
controllers like the 3ware raid cards can do the same with ide drives 
and also offload the work from the main CPU.

-- 
   Les Mikesell
    lesmikesell at gmail.com