SATA Port multipliers: Are we getting hosed?

[DougLite]

Well, as most of you know, port multipliers are a part of the SATA 3G specifications. They allow multiple drives, typically four or five, to be connected to a single SATA 3G port. However, adoption on them has been very slow, and they are just a dream for most of us.

Now, for the big RAID controller makers (3Ware, Acrea, Broadcom/RAIDCore, etc) the principle pricing mechanism on SATA RAID adapters is the number of ports on the card. As an example, 4 port 3Ware boards go for ~$250-300, while 8 port units fetch ~$450-500, and 12 port units command ~$700 With support for port multipliers, the 4 port card allows for 16 or 20 drives to be attached, blowing away the functionality of the 12 port card without port multipliers, all while requiring less PCB space.

So, what's holding up adoption of this exciting technology? I have no choice but to believe that controller makers are out to protect high profit margins by forcing customers that require large numbers of drives to purchase the controllers with more ports. How long will it be before one of the major RAID host adapter makers decides to undercut everyone else by offering port multiplier support? Will such a product change what you would buy to host a large RAID array?

 

[doormat]

Exactly! I was thinking about this the other day... why not buy a 4 port card and then a bunch of port multipliers, or better yet, port multipliers built around 4 drive cages (that fit into 3 5.25" bays). (I dream of that big TT Xaser case with the 12 or however many 5.25" drive bays with these cages in them.. mmmmm)

The only reason to buy a big 12-port card is if you think that the drives on your port multiplier are going to saturate the link, and that you'll need and want to pay for the extra bandwidth it would provide. But with a 300MB/s link, that doesnt seem like an issue to me, at least not for another few years, and by then we should have 600MB/s links (maybe 4 of those rumored new 150GB raptors could saturate a 300MB/s link - thats sustained reads of 75MB/s each, which seems plausable based on what I've read).

If I were in charge, I'd just make 4 port and 8 port cards, and support PMs and have the firmware limit the number of drives supported. Two designs, multiple firmwares to support 4, 8 , 12, 16, 24, 32, ... drives per card. You could even be flexible and allow people to buy firmware upgrades instead of new cards - want to move from 8 drives to 12 or 16? Here is the price to upgrade the firmware to support that many drives.

 

[DougLite]

If I were in charge, I'd just make 4 port and 8 port cards, and support PMs and have the firmware limit the number of drives supported. Two designs, multiple firmwares to support 4, 8 , 12, 16, 24, 32, ... drives per card. You could even be flexible and allow people to buy firmware upgrades instead of new cards - want to move from 8 drives to 12 or 16? Here is the price to upgrade the firmware to support that many drives.

And that 'price' would be almost pure profit for the controller maker, as they would not have to provide a new controller card to add the functionality, just a download from a secure website. Accountants love 'pure profit'

 

[Ender]

Do you have any pictures of what the cabling or hard drives that meet the 3G specs?

I'm just curious as to how its going to be like... Will it be the way SCSI cables are ? 1 cable with multiple ports ? Or will next generation hard drives have 2 SATA ports so that you "chain" the drives and the final one connects to the MB/Controller?

Either way I'm fairly certain that my 9500-S wont be upgradeable to support it

To answer your final question it definately would change my buying decision, the reason I went with the 8 port 3ware card was so that I could future proof it. As it is now I'm using 5 ports so there is still room for expansion but chances are I'll get larger drives like 4-500gig models (currently have 250's) before I buy more 250's. If the technology was available now I would have bought a 4 port card for the mentioned reasons...

 

[doormat]

And that 'price' would be almost pure profit for the controller maker, as they would not have to provide a new controller card to add the functionality, just a download from a secure website. Accountants love 'pure profit'

Yea that was the business man in me. A little job making sure it was secure and you cant pass the firmware around on the internet, and the job is done. I should patent that business model!

The computer geek in me says "F- those jerks" and would try and hack it, of course.

You want to start a company Doug? Lets get rich.

 

[DougLite]

Do you have any pictures of what the cabling or hard drives that meet the 3G specs?

I'm just curious as to how its going to be like... Will it be the way SCSI cables are ? 1 cable with multiple ports ? Or will next generation hard drives have 2 SATA ports so that you "chain" the drives and the final one connects to the MB/Controller?

Either way I'm fairly certain that my 9500-S wont be upgradeable to support it

To answer your final question it definately would change my buying decision, the reason I went with the 8 port 3ware card was so that I could future proof it. As it is now I'm using 5 ports so there is still room for expansion but chances are I'll get larger drives like 4-500gig models (currently have 250's) before I buy more 250's. If the technology was available now I would have bought a 4 port card for the mentioned reasons...

It is my understanding it will be more like the SCSI model. You would either have a cable with multiple connectors, or a backplane that can house 4 or 5 drives with a single data cable connector. One port and cable for a four drive backplane will start all sorts of modular storage madness

 

[michaelgildersleeve]

Are there any updates on this? I put in a water cooler in my system, and the GPU block blocks one of my PCI slots. I had this slot reserved for a 4x SATA controller when I needed it. I have room in my system for 2 more stacks of 4 hard drives and I have one more open PCI slot. I don't want to have to buy a 8x controller because they are rediculously expensive. Is there any other way to control multiple drives? External firewire drives often allow daisy chaining. Is there a way to daisy chain hard drives without an external case? I would really like to keep my stacks of hard drives consistant. I don't mind what's in the back of them (adaptors or such), but I would like the front of the stacks to look the same.

Thanks