View Full Version : ATA CPU overhead compared to SCSI

06-10-2001, 06:36 PM
Any benchmarks available which show differing Loads ATA drives&interfaces place on a CPU and a system in general compared to SCSI??

Im told ATA taxes CPU where as SCSI does not due to dedicated chips on SCSI controller cards. I'd like to see some quantifiable figures if there is any available to help determine a SCSI setup or an ATA-100 disk setup.

Cant have I/O systems taking too much away from the CPU when placing systems under load now can we.


06-10-2001, 07:59 PM
ATA does not tax the CPU like it used to. From what I understand DMA allows ATA/IDE to work fairly fast. Where you run into bottlenecks is when two drives on the same channel are trying to work. Only ONE can work at a time.

You might want to try barefeets. They should have some tests. Not sure how thorough. For speed and latency the 15K Cheetahs are the BEST. Running these with a dual channel U160 card would crush ANY IDE/ATA setup to dust - easily. Its just a matter of you spending all that money and actually needing all that bandwidth.

I think in real terms you can get about 100 to 200MB/s throughput on a high end SCSI system. This system will also be guaranteed for 5 years (vs. 3 for IDE/ATA). It will probably last 7 to 10 years - maybe more....
SCSI CARD ~ $200 to $600
Cabling ~ $0 to $600
Drives ~! $300 to $500 each
SoftRAID $150

I think the last time I priced it out, it was about $2600 for the ULTIMATE setup - being 4x18GB 15K Cheetahs and the ATTO U160x2 card... I already have SoftRAID and if its internal you may not need any extra cabling.

I am not aware of any ATA100 cards for the Mac, yet. There are no good hardware RAID setup's for the Mac, that I know of. This may change with OS X Server2... but it will take some time.

So long and thanks for all the fish!