SATA 2.5 Discussion

[Scroatdog]

DougLite,

So I just read the front page news link about the SATA 2.5 spec coming online in Novermber. Since some of the features mentioned are already present in the SATA II spec, do you think we will be looking at a chipset driver update to bring motherboards up to SATA 2.5 standards, or is this going to require a new motherboard rollout for the manufacturers???? Just curious. Nothing I read seemed to point to a necessary hardware change, aside from the drives themselves, of course......

 

[DougLite]

First off, there are plenty of people out there that know more than me on such matters. Confucius say "He who talks the most may not necessarily know the most." UlCompE02 in particular works in this business, and knows a lot more about interfaces than I could ever hope to. I am humbled that you would address a question specifically to me, but at the same time, I wouldn't dismiss the knowledge and insight of other members. If you have a question specifically for me, please send me a PM.

My take on SATA 2.5 is that it's main goal is to make drives incorporating next gen features easier to market. As we all know, SATA-II is meaningless now, as the drive makers have used it to designate drives with 3 gbps transfer. SATA 2.5 is more of a consolidation, allowing the makers to apply a single term to drives that support 3 gpbs transfer, NCQ, hot plug, staggered spinup, port slectors/multipliers AND eSATA (external SATA). The key word here is AND Before, makers had to have a laundry list of the supported features, now they can simply say "SATA 2.5" - presuming they incorporate all of the features.

This means BIOS/firmware updates for some, if not all, SATA hosts for port multiplier/selector support. Drives that support 3gbps transfer and NCQ should be good to go for the most part. Given the blurring lines between consumer and nearline enterpise drives, hot plug and staggered spinup support should trickle down to the vast majority of drives fairly soon, and the drives shouldn't "care" about port multipliers/selectors and eSATA.

 

[evenglow]

I'm not sure but it sounds like all they are doing with SATA2.5 is to combine all the specs and whitepapers for SATA1 and SATA2. I read the PDF and it doesn't mention anything new.

 

[doormat]

The one thing I noticed is that they prolly could have called it SATA-II Professional or some crap like that and it would have meant the same thing. Its just that all the optional features that were defined in SATA-II are now required in SATA 2.5. Your SATA 2.5 drive, or SATA 2.5 host will support all these features. I just cant wait for that port multiplier/backplane.

 

[tiebird321]

I just cant wait for that port multiplier/backplane.

where would be a good place to find out more on this
i'm curious if its a M/S design or an independent ID design or a linked LUN style thing

the bandwith of a 3gb link is such that your running way above what you can get for continuous data transfers(from a 7.2k drive). you could very effetivly place 3-4 drives on each channel to maximise the data bandwith usage. which would make running large disk arrays more affordable because you would only need a 4 port card in place of a 12 port card to get similer performance and capacity

 

[doormat]

DL brough it up in this thread, about port multipliers and whatnot. I havent seen any in production or for sale.

 

[unhappy_mage]

I just cant wait for that port multiplier/backplane.

QFT

How will port multipliers work? Basically several drives appear as one, or as multiple drives? One scenario I can think of is a little thingy that has 1) raid 0, 2) raid 5, or 3) jbod logic in it, and appears as a single disk to the OS. 4) is that you'd just see several disks. Only the last would let you use a bunch of disks on a smaller controller; this would be the best IMNSHO.

And how about an external port multiplier? That'd be sweet for backup space...