Cables: 4 SATA vs. 1 SAS breakout

[AgedReason]

So far I've not been able to find or process an answer to which is the better route to go (assuming there IS an better route).

I'm getting a X10SL7-F and intend to connect my WD Reds to the SAS2 ports.

Are there any advantages/disadvantages (one way or the other) to connecting each of the 8 SATA drives to their own individual SAS2 ports as opposed to using breakout cables to connect each set of 4 SATA drives to one SAS2 port?

Or do I, once again, have the entire concept screwed up?

 

[Bidule0hm]

The SAS ports on the X10SL7-F are already SATA connectors and not SFF-8087 connectors, you just need standard SATA cables ;)

 

[pirateghost]

No special cables needed on that board. Just plugin 14 drives

 

[AgedReason]

Cool. So, I figured that SATAs will work.
Just so I understand, what I'm hearing is that SFF-8087s will NOT work?

 

[pirateghost]

Cool. So, I figured that SATAs will work.
Just so I understand, what I'm hearing is that SFF-8087s will NOT work?

There are no SFF8087 ports on the board.

 

[Bidule0hm]

Yep, exactly.

Edit: ah, @pirateghost has been faster :P

 

[AgedReason]

Woohoo! Fundamental misunderstanding for the win!

So I need to go read up in detail more on how SAS2 differentiates from SATA and figure out what gave me the idea that 4 SATA drives could connect to the SAS2 port...and just what the heck does connect to an SAS2 port.

 

[Bidule0hm]

SAS and SATA are protocols, SFF-8087 (and the others SFF connectors) and SATA connectors are connectors. You can use SAS protocol with SATA connectors, and SATA protocol with SFF-8087 connectors (but I never seen the later be done).

What you have on the X10SL7-F is 6 SATA connectors connected to a SATA controller and 8 SATA connectors connected to a SAS controller. You can plug up to 14 SATA drives with standard SATA cables to the MB.

With reverse breakout cables and SAS expanders you can connect more than 8 drives on the SAS controller but it's another story.

 

[Ericloewe]

SATA protocol with SFF-8087 connectors (but I never seen the later be done).

ASRock's voodoo-shrunk X10SL7-F does that, to overcome space constraints. A few other boards do, too.

 

[Bidule0hm]

Interesting thing to know :)

 

[AgedReason]

Oh. I was assuming that form and function were mutually exclusive. Not so.

So then, in this case, the X10SL7-F's SAS ports were likely put in SATA form to be immediately useful for SATA devices if I wasn't planning to use them with an expander.

I think I'm beginning to understand why I was having such a hard time finding the information I wanted on the web: I was asking all the wrong questions. Thanks for the help.

 

[bestboy]

Maybe this helps to clear things up:
Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

 

[Bidule0hm]

So then, in this case, the X10SL7-F's SAS ports were likely put in SATA form to be immediately useful for SATA devices if I wasn't planning to use them with an expander.

Yes, exactly that ;)

 

[jgreco]

Maybe this helps to clear things up:
Don't be afraid to be SAS-sy ... a primer on basic SAS and SATA

Somebody reads my stickies. <<happy>>

 

[AgedReason]

Somebody reads my stickies. <<happy>>

I"ll be honest, I read that sucker over and over. Then I read it again after each of these replies. (In fact, I've got it open again right now.)

I interpreted the information about cabling (incorrectly, obviously) to mean that there was a degree of interoperability between the two, that a SATA drive connector will fit on a SAS2 port, but a SAS2 connector will not fit on a SATA port. The SATA connectors used on the X10SL7-F's SAS2 ports reinforced this assumption.

Naturally, this left me confused and I felt I needed some clarification. On the one hand, it appeared to me that up to 4 SATA drives could be utilized by a single SAS2 port on my MOBO via breakout cabling alone; while on the other hand, a lot of things about that just weren't adding up. I scoured the forum best I could and found some interesting info, but nothing that seemed to directly apply. (Of course, now I know why.)

Anyway, here we are. I still can't say I definitively grasp the nuances, but I think I have a better idea of the broader concept now, for which I am grateful.


ps. and I did RTFM ;) (still working on UTFM) & the stickies really give a solid jumping off point. I'm about to be all over the "Building, Burning & Testing" one.

 

[pirateghost]

I"ll be honest, I read that sucker over and over. Then I read it again after each of these replies. (In fact, I've got it open again right now.)

I interpreted the information about cabling (incorrectly, obviously) to mean that there was a degree of interoperability between the two, that a SATA drive connector will fit on a SAS2 port, but a SAS2 connector will not fit on a SATA port. The SATA connectors used on the X10SL7-F's SAS2 ports reinforced this assumption.

Naturally, this left me confused and I felt I needed some clarification. On the one hand, it appeared to me that up to 4 SATA drives could be utilized by a single SAS2 port on my MOBO via breakout cabling alone; while on the other hand, a lot of things about that just weren't adding up. I scoured the forum best I could and found some interesting info, but nothing that seemed to directly apply. (Of course, now I know why.)

Anyway, here we are. I still can't say I definitively grasp the nuances, but I think I have a better idea of the broader concept now, for which I am grateful.


ps. and I did RTFM ;) (still working on UTFM) & the stickies really give a solid jumping off point. I'm about to be all over the "Building, Burning & Testing" one.

If you start messing with expanders, then reverse breakout cables come in handy. I have 20 disks attached to 4 of those SAS ports on that board.

 

[AgedReason]

If you start messing with expanders, then reverse breakout cables come in handy.

Yeah, that was the part I missed: required expanders. I initially figured that a breakout cable could just connect directly to 4 drives on one end and the MOBO on the other and the onboard controller somehow magically sorted them all out. I thought expanders were for doing more. It all seemed a little fishy, but stranger things have happened. Glad I asked. The concepts are lining up now.

 

[Ericloewe]

Yeah, that was the part I missed: required expanders. I initially figured that a breakout cable could just connect directly to 4 drives on one end and the MOBO on the other and the onboard controller somehow magically sorted them all out. I thought expanders were for doing more. It all seemed a little fishy, but stranger things have happened. Glad I asked. The concepts are lining up now.

Your confusion probably stems from the SFF-8087 connector.

SAS has two different host-side connectors, which are electrically compatible: The legacy SATA connector and SFF-8087, which bundles together four independent SAS lanes plus some sideband stuff (for drive LEDs and stuff). On the drive side, there is only one connector, which is based on the SATA connector (to allow for backplanes to accept SATA and SAS) but adds signalling for a second channel (for multipathing).

SFF-8087 is just a handy way of reducing cable clutter. Think of it as four SATA cables wrapped in one shroud (it's more complicated than that, so don't try to improvise your own).
A breakout cable just unbundles the individual connections (or bundles them together, if it's a reverse breakout cable).

 

[AgedReason]

Your confusion probably stems from the SFF-8087 connector.

Yup, at it's core, that's what got the ball of confusion rolling. I tried to reconcile what the SFF-8087 connector was designed to do and what I saw on the X10SL7. I fell into a classic logical fallacy. (If the connector is made for SAS2, and the board has a SAS2 port, then the connector will fit on the board.) Wrong.

I appreciate the clarification.

 

[jgreco]

I"ll be honest, I read that sucker over and over. Then I read it again after each of these replies. (In fact, I've got it open again right now.)

A large part of the reason I write stickies is to de-mystify things. I try to do this with some attention paid to the fact that new users lack the practical experience with stuff to get up to speed.

You could do everyone a large favor if you would re-read the sticky with a critical eye towards my writing and your state of mind, and let me know where you went awry. You are encouraged to be viciously critical of my writing, if needed, as long as it is vaguely constructive in nature. I would really like to make sure that people are put on the right track by the stickies I've written because I've invested a fair amount of time and effort trying to make them usable and accessible. You are in a much better position to judge where my writing sucks than I am, and any hints you can provide are gladly accepted.