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the WD special edition drives with the 8mb cache aren't quite as fast as scsi, but they're closeQuote:
Originally posted by CoOliOgUy
hmm i've read about that 8 meg WD thats supposed to be upto par with SCSI performance, problem with SCSI is its so expensive..
I think the difference is really negligable unless you are dealing with a massive array. SCSI isnt worth it anymore in my opinion
AFAIK, most modern drives arent utilising ATA100 never mind 133.
For example, the Western Digital WD1200JB Special Edition is currently the fastest IDE drive on the market. Yet it is only ATA100.
Its maximum, burst transfer rate is around 48Mb/sec. It averages out at around 29Mb/sec.
This compares to 41Mb/sec and 25Mb/sec for the Maxtor D740X, which is an ATA133 drive.
Comparing this to say the Seagate Cheatah 36ES, a 36Gb, 10,000 rpm SCSI hard disk, the transfer rates are 54Mb/sec and 43Mb/sec respectively.
As you can see, the IDE drives do not even use ATA66 to their fullest potential, since the fastest transfer rate achieved by the fastest drive is around half of what ATA100 is capable of transferring through its interface (100Mb/sec).
With that mind, remember that it matters not what the interface can do, its what the actual drive can do. You only really utilise ATA100 when using two such devices on the interface.
With that in mind, SCSI is better because its interface is faster and can support more disks, but the main reason why you find SCSI drives faster, is simply because they are better quality drives. It really has not much to do with the interface when talking about 1 or 2 drives. Beyond that SCSI walks away with it.
** EDIT ** To add SCSI performance results
I would think it would be easier to implement on SATA. From what I hear it is a lot closer to SCSI than IDE is. I could be wrong. But yes we are still not even reaching ATA66 speeds. Althoug it looks like I surpass ATA66 for half a second or so on my WD drive :) It could use the boost in access time that 10K drives would offer.Quote:
Originally posted by Tekime
AFAIK, current IDE drives barely utilize ATA133, I mean for most drives the difference between using ATA100 & ATA133 is negligable. Truth be told, they could very well hold off until Serial ATA but I wouldn't be surprised to see 10,000 RPM IDEs around. If it's worth it to manufacture, there will be plenty of customers who don't grab SATA the second it hits the streets.
Eric
The SCSI controllers also contain a track cache. Some models of the older Ultra 160 line of controllers from Adaptec can have up to 132MB of cache.
The new Ultra 320 SCSI controllers can transfer data at 320MBytes per second. Adaptec's offering has 2 channels on a single board for a whopping 640MBytes per second transfer rate from up to 30 drives.
SCSI and ATA are simply different, non-competing products appropriate for very different computing situations.