SFF-8087 and SFF-8643 - Confused!

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twseal77

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I need some help.

I'm looking to build a new server and I've never used SAS before and I'm a little confused about backplanes and connecting them.

Both mother boards I'm looking at have 2 SFF-8643 connections that state they support up to 16 HDD's. I'm looking at cases with 16 hot swap bays. In most rack mount cases I see have 4 8087 connection.

I know that standard SFF-8087 only supports 4 lanes on a single connector. SFF-8643 supports 4 or 8 according to everything i've read, including Wikipedia reference (https://en.wikipedia.org/wiki/Serial_Attached_SCSI) 0n a single connector.

The problem is, if SFF-8643 supports up to 8 on a single cable or 16 on two, then why would I need to connect to 4 ports on the case backplane. Can I connect to two and achieve the same results, or do I have to use all 4.

I guess I just don't understand why an HBA with two 8643 can support 16 HDD's with two connectors would need 4 connectors on the other end.... which would require a second HBA that also supports 16. Then I would have 2 HBA's supporting 32 HDD's just to be able to connect to 16 drives. Is the real issue here just simply having a case with a backplane that has a build in expander?

Am I getting the number of HDD's it supports logically and the number of HDD's the cable supports physically without an expander confused? (I.e. the card can handle 16 HDD's using two 8633 connectors as long as I have an expander. Or it is limited to 8 total HDD's for two connections (4 for each cable) without an expander?)

To the cable itself, am I not understanding the cable? Is an SFF-8643 basically the same concept of two SFF-8087's at 6gb/s combined to give 12gb/s speed. If so, if I used an expander to basically 'split' or divide out the SFF-8643 into two lanes supporting 4 devices (or in this case two connectors split to 4 lanes supporting 4 devices each) would that then reduce the speed to 6gb/s. To further that, If I got two HBA cards both with two SFF-8643 connections, then giving me one to one SFF-8643 to SFF-8087 (so four SFF-8643's to four SFF-8087's) would that then give me full 12gb/s speed?

The motherboards and cases I'm considering are:
Motherboard - SUPERMICRO MBD-X10DRC-LN4
Case - SuperMicro SC836BE1C-R1K03B
Or
Motherboard - Asus Z10PE-D16/4L
With ASUS PIKE II 3108 8-port SAS HW RAID card
Case - Norco RPC-3116 3U

Asus option might be a little cheaper, both boards seem nice, but leaning more to SuperMicro because the Case seems a lot more solid and better, plus more documentation and support. (Plus I wouldn't have to buy another Card for SAS since SuperMicro has it built onto the motherboard.)

Am I understanding this correctly? - I hope this makes sense to anyone who reads it.
 
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Ericloewe

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First of all, your text is nearly unredable and is in desperate need of pargaraphs.
The problem is Both mother boards i'm looking at have 2 SFF-8643 connections, while most Cases have SFF-8087.
SFF-8643 is simply the newer connector. It's 100% electrically compatible with SFF-8087.
Do I need to have 4 8643 connections for the mother board or HBA card to connect to the 4 8087 backplane ports?
Yes. Or from an expander.
Seems silly to have to do that since 8643 carries 8 drives
Not sure how you reached that conclusion, but it's not correct. 4 lanes per connector.
 

twseal77

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First, thanks for the response, Second, I edited my first post... hopefully it makes a bit more sense. I was trying to gather my words and figure out how to ask what I didn't know how to ask. Please take a look at the first post again, perhaps it may be a little more clear. I think I may understand it now, but I'm not 100% sure.
 
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BigDave

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Many of the questions you asked about (the physical controller to backplane connections),
can be answered by reading the pdf manual of the backplane model used in the chassis
(at least for a Supermicro brands) you are considering for purchase.

The documents will contain lots of good basic information as well as specifics for that model backplane.

Attached below is for use with the backplane for the Supermicro 3U box you mentioned.
I hope this helps, I know this was the start for me to begin to understand these same questions.
 

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twseal77

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Oct 22, 2016
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First of all, your text is nearly unredable and is in desperate need of pargaraphs.

SFF-8643 is simply the newer connector. It's 100% electrically compatible with SFF-8087.

Yes. Or from an expander.

Not sure how you reached that conclusion, but it's not correct. 4 lanes per connector.
First, thanks for the response, Second, I edited my first post... hopefully it makes a bit more sense. I was trying to gather my words and figure out how to ask what I didn't know how to ask. Please take a look at the first post again, perhaps it may be a little more clear. I think I may understand it now, but I'm not 100% sure. - and thanks for any help or direction you can provide on this!
 

twseal77

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Oct 22, 2016
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Many of the questions you asked about (the physical controller to backplane connections),
can be answered by reading the pdf manual of the backplane model used in the chassis
(at least for a Supermicro brands) you are considering for purchase.

The documents will contain lots of good basic information as well as specifics for that model backplane.

Attached below is for use with the backplane for the Supermicro 3U box you mentioned.
I hope this helps, I know this was the start for me to begin to understand these same questions.

Thanks, I'll read this and hopefully have more insight.
 

twseal77

Cadet
Joined
Oct 22, 2016
Messages
7
Many of the questions you asked about (the physical controller to backplane connections),
can be answered by reading the pdf manual of the backplane model used in the chassis
(at least for a Supermicro brands) you are considering for purchase.

The documents will contain lots of good basic information as well as specifics for that model backplane.

Attached below is for use with the backplane for the Supermicro 3U box you mentioned.
I hope this helps, I know this was the start for me to begin to understand these same questions.

This doc is way more simple than the one I previously looked at. The other I downloaded was too complicated and had too many versions on it to sort through what I was looking at. Thanks again!.
 

Ericloewe

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The motherboards and cases I'm considering are:
Motherboard - SUPERMICRO MBD-X10DRC-LN4
Case - SuperMicro SC836BE1C-R1K03B
Or
Motherboard - Asus Z10PE-D16/4L
With ASUS PIKE II 3108 8-port SAS HW RAID card
Case - Norco RPC-3116 3U
Let's go through a few important questions:
  • Why on earth are you considering dual-socket boards!? What do you hope to gain?
  • Both end up using LSI SAS3108 controllers, which are not a good choice. SAS3008 is fine, but the SAS3108 isn't.
  • What is the inded use for this server?
 

twseal77

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Oct 22, 2016
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Let's go through a few important questions:
  • Why on earth are you considering dual-socket boards!? What do you hope to gain?
  • Both end up using LSI SAS3108 controllers, which are not a good choice. SAS3008 is fine, but the SAS3108 isn't.
  • What is the inded use for this server?

The main purpose is to run Windows Hyper-V server 2016, then on that I would be running an Active Directory Domain Controller on Windows server 2016, another server running Windows SQL server 2016, another running Exchange server, and another running SharePoint Server (SharePoint being the biggest memory hog)

Having said that, biggest goal is to have plenty of RAM and processing power for Hyper-V servers along with the possibility of some extra stuff I may run, including possibly being a backup for my existing QNAP NAS. It is mostly used at home for learning environment and some other stuff I want to use... along with a large Cisco rack I have. I know that technically the Motherboard is overkill because I only really need about 128gb of RAM running on it. There are other 'smaller' boards that meet my needs just fine without being overkill, but these options are, believe it or not, cheaper overall than the smaller ones. Which is why I was looking at them specifically. - Otherwise I would have gone with a smaller choice.

As for a 3u case, I can technically go with a 2u just fine, but again, price is about the same 2u or 3u and I figure why not, for future expansion if I wanted, and more fans, better cooling, etc.

I'm also trying to make it as quiet as possible, since it would be on a 42u Cisco Rack I have in my office which is loud enough by itself (working on my CCNA and CCNP and I got a good deal on a nice rack and a lot of Cisco equipment - Overkill - but I got about $6000 worth of cisco routers, switches, wireless controllers, firewalls, WIC's, Fiber, you name it, for $1000, so I couldn't pass that up.

Also I would like to run it with Raid 50 and IPMI ports are important since I remote in a lot and want to be able to remotely reboot and manage that too... etc, etc.

I'm also starting my Masters in IT, and starting an engineering position at work... so I want to expand my knowledge as much as possible and this will come in handy when I have to do my final work on my Masters degree. I know all the other stuff, I've just never built anything with SAS before, only older SCSI, SATA, etc. SAS is new to me and all of the documentation I previously looked at was over complicated and didn't get to the point very well.
 
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twseal77

Cadet
Joined
Oct 22, 2016
Messages
7
Many of the questions you asked about (the physical controller to backplane connections),
can be answered by reading the pdf manual of the backplane model used in the chassis
(at least for a Supermicro brands) you are considering for purchase.

The documents will contain lots of good basic information as well as specifics for that model backplane.

Attached below is for use with the backplane for the Supermicro 3U box you mentioned.
I hope this helps, I know this was the start for me to begin to understand these same questions.

BigDave,

Just want to say thanks once again. I had a chance to read that doc. It definitely cleared things up for me. Since that backplane has expander build in, as long as I get that one with the SFF-8643 connections I'll be able to use just the two connections directly to two on the backplane. Thanks again, much appreciated!
 
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