I thought the SCSI performance difference was CPU

Post #83,155

2/21/03 10:23:20 AM

Since the IDE controllers use some CPU, and the SCSI controllers do not.

Also, SCSI is supposed to be better for chained devices, isn't it?

I'm no expert, by any means... but this is how I recall it...

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-scott anderson

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Post #83,157

by inthane-chan

2/21/03 10:38:03 AM

Still would make sense.

Since the SCSI controller electronics are more complex, possibly that is where the enhanced testing requirement pops in, to verify all is working according to plan?

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Post #83,160

by folkert

2/21/03 10:44:10 AM

Serial ATA... may have broke that assumption...

Serial ATA, supposedly you can chain upto 61??? or was it 29?? devices per serial ATA chain...

And, I once thought that too... but now it seems most of the chipsets are doing the work... older chipset may experience those problem... but the PDC and HPT chipsets seem to be doing most of the work...

Now, I can burn-up processor just as much with SCSI as I can with IDE... If you look at those chipsets anyway... they are addressed as SCSI now anyhow. (At least in Windoze... :~O)

b4k4^2

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Post #83,315

by a6l6e6x

2/21/03 9:49:03 PM

Re: I thought the SCSI performance difference was CPU

Yep. Years ago, I wrote what was in a effect a SCSI device driver on a roll your own embedded system. This was on a [link|http://www.webopedia.com/TERM/V/VME_bus.html|VME bus] system, but the SCSI controller as well as the hard drives themselves are much more capable. For example, it is possible to tell a drive to low level format itself with some uncommon sector size and cause interrupt when it was done. It was possible to queue up a whole bunch of non-contiguous sector reads to a drive and get a single interrupt when it was done. It was possible to have 7 drives doing I/O simultaneously.

I don't know how fancy the PC SCSI controller are, but I would expect them to be similar in capability.

Alex

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