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."

firewire

[diesel66]

a good option to consider. i don't know of any mobo makers that offer it, but it's easy to add on. i think a speed bump to 800 Mbps is around the corner. include the fact that it's hot-swapable, 127 devices or something, etc...

Where are the drives?

[charnov]

Okay...I have a SATA equipped mobo on order which comes in in two weeks. What I want to know is: where are the hard drives? And no, I don't mean the drives that are standard ATA100 that have converters. I mean Seagates native SATA drives. They demoed supposed "production" pieces back in Fenruary.

I believe..

[iONiUM]

I believe the general conception that SCSI is too expensive for the home user is going to make it hard for SCSI to pick up now. Although SCSI is much faster (and better for business in my opinion), I think IDE will continue to rule with it's slower perfomance and cheaper prices the home market. Quite a shame though, IDE seems to always be so slow when compared to the incredibly fast SCSI drives out... but then again, the size of IDE w/ current prices means you can get a huge hard drive for relatively cheap, which is almost impossible with SCSI.

Internal firewire?

[Anonymous Coward]

While this is not important (hence my score:0 AC post) i would just like to ask a quick question related to this story topic i have been wondering about, as there tend to be many people on slashdot with more knowledge than i, so maybe someone will have an answer.

Does anyone know if there have been any steps anywhere in the Industry toward the eventual offering of internal hard drives that use FireWire? Would that not be cost efficient?

just like the RAMBUS story

[lingqi]

remember back when RAMBUS said: we will provide an architecture with very narrow bus but extremely high speed to make up for it? (the *original* RAMBUS specs) -- beside the royalties and whatnot -- it actually (technology discussion only) had merits in that the PCB design was greatly simplified because of less crosstalk, easier routing, etc etc.

and then, people demanded more bandwidth... so now we have double / quad pumped RAMBUS channels -- in the end (today) it's back to 64-bit data-bus *anyhow*... except with an architecture that's not designed for parallel operation.

do anybody see some parallel (ha!) here?

i am guessing (or, predicting) that serial ATA / SCSI will go the same route. i really hope that it won't -- because if it did, our lives will all be kinda rough -- but it probabbly will.

sigh...

Re:Serial ATA v. SAS

[iKitty]

Your performance assumptions are flawed. U320 SCSI allows 320MB/sec for the entire SHARED SCSI BUS (15 drives). S-ATA gives you 150MB/sec to EACH drive; the SATA controllers support a Direct Port Access (DPA) mode that allows DMA transactions to proceed simultaneously to all drives. With the new Seagate and WD drives having the larger 8MB cache in each drive we will see decent per drive performance and in large drive arrays (>8 drives) the performance should beat the pants off of SCSI.

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.