[NTLUG:Discuss] SCSI drives

[Chris Cox]

Greg Edwards wrote:
> Vaidya, Harshal (Cognizant) wrote:
> 
>> Hi All,
>>
>>   Can anybody explain me what is the difference between a normal Hard 
>> Drive
>> and SCSI drive.
>>
>> Thanks and Regards,
>> Harshal Vaidya
> 
> 
> The short answer.
> 
> SCSI is traditionally faster and more efficient than IDE.  Recently IDE 
> has narrowed the gap in performance but still has some design issues 
> that cannot overcome the performance advantages of SCSI.  You usually 
> won't find PC motherboards with onboard SCSI controllers so you need a 
> card (PCI) to use SCSI drives in a PC.

The fastest most contemporary IDE on the fastest bus... even
striped across two drives will not come close to the last generation
of 10K SCSI drives... and certainly not close to the current
generation of 10K and 15K.  At best you might break the 8ms
access time on IDE, but SCSI is currently at less than 4ms
and with data xfer rates which range from 75M/sec to 50M/sec...
you'll be fortunate to get 50M out of IDE on the fast edge (and
it will fall to 20-30M on the slow edge).

http://www.storagereview.com

> 
> One major advantage to SCSI is that a single controller can chain 
> anywhere from 7 to 15 SCSI devices (inside or outside the case) together 
> while IDE can only chain 2 (inside the case only) together.  IDE can 
> only handle disks while SCSI can handle any device type.  SCSI allows 
> each device to transfer independently so that each device can transfer 
> data concurrently.  In general IDE is forced to run at the transfer rate 
> of the slowest device in the physical chain while SCSI can transfer at 
> different rates to different devices on the same chain.
> 
> A major disadvantage to SCSI vs IDE is the $$$$.

You're IDE drive will likely die under high load within 2 to 3 years.
So perhaps SCSI isn't that expensive when you consider the
much longer MTBF and the much, much faster access times (trust
me, it's not even close, though many will try to convince you
otherwise).

> 
> MadHat gave you some good links for the long answer.
> 
> Good luck,

My next machine will be SCSI.
Costs more... and you get a whole lot more.