Serial ATA and Serial SCSI

aibrahim writes "In the recent Slashdot article about Serial ATA some people wanted to know where SCSI was going, and if Serial ATA could deal with some higher end workstation and low end server requirements. Apparently it has been decided that Serial ATA 2 (pdf doc) and Serial Attached SCSI are the answers."

Comments

ATA/SCSI distinction

[XNormal]

With current silicon integration levels there is no real reason why SCSI should be more expensive than ATA. They could have just merged them and perhaps emulated braindead ATA on top of SCSI to keep compatibility or something if anyone really wants to.

I'm pretty sure the only reason they keep the difference is to be able to charge more from people building servers. It's purely a marketing and price positioning decision.

So?

[gerardrj]

They still don't say that serial ATA will support more than two devices per channel. In fact they say it will be software compatible with ATA in its current form, suggesting it continues the master/slave relationship.

Today's drive media can only reach 40MB/s reading from the platters for short bursts, if their lucky. Normally they'll read/write about 20MB/s. What's the point of another boost in speed of ATA (to the suggested 150MB/s) when you will only ever be able to use 80MB/s of that. Oh, that's right... the ignorant users need bigger numbers on their cardboard boxes to show off to the neighbors.

Does anyone have any information on a HD soon to be released that will offer a quantum leap of read-from-meadia performance to something like 75MB/s? That's more than triple the current read-from-meadia speeds, and they seem to only ever increase the speeds by about 1-2MB/s each year.

SCSI makes sense having very high bus bandwidth, as you can connect quite a few devices and use the connect/disconnect to send simultaneous reads/writes to multiple devices. In that scheme, you can keep most of your drives operating at the same time. Of course Apple has shown that at least for a small RAID, multiple independent ATA channels are just as fast and lower cost than a single SCSI channel. I persoanally have a difficult time thinking that multi-ATA design would scale well to a 32 drive RAID, where a dual channel SCSI would shine.