Question Regarding Backplane MINI-SAS to HBA Connections

[dbm]

Hello,

 

Finishing a build right now for mass storage needs, and am a bit confused on something.

 

I have already read quite a bit, and gained some knowledge from the thread here (cheers): https://linustechtips.com/main/topic/597828-connecting-24-drives-to-1-motherboard/

 

I have a [discontinued] Chenbro NR40700 case with a couple of backplanes for mounting 24 drives each, for a total of 48 drives. I am going to start out with about 7 drives:

• 5x 16TB Seagate Enterprise HDDs
• 1x 2TB HDD (for boot + misc data)
• 1x 1TB SSD (misc data)

The boot drive and SSD are both separate from the backplanes, and are currently connected directly to the motherboard's 2 SATA ports. For the rest of the drives, as it seems my motherboard only has 2 SATA connectors, I got an HBA card (LSI Broadcom SAS 9300-8i). The motherboard I am using is a Supermicro X11DPi-NT.

 

For now, regardless of how "silly" or dubious it sounds, I am wanting to just run all these drives independently of each other, so the server effectively just sees the 7 drives. (No RAID, JBOD, ZFS, or any such thing; I am going to be virtualizing with Hyper-V, and have already distributed multiple copies of my virtual disks in case of a physical disk failure)

 

I have attached the manual for the backplanes for reference.

 

I'm new to this mass storage whole mass-storage thing, so I have a few questions:

• The NR40700 case has 2 backplanes, each with 3 Mini-SAS connectos which I assume I am supposed to connect something to (there's CB1_Mini SAS IN, CB2_Mini SAS IN/OUT (switchable), and CB3_Mini SAS OUT.
• The HBA card I have gotten is flashed in IT mode (for passthrough), and is the LSI Broadcom SAS 9300-8i, with what appears to be two SFF-8643 connectors.

 

My questions are:

• I am assuming that I must somehow connect the SFF-8643 ports on the HBA to the backplane, is this correct?
• If so, since there are 3 connectors on the backplane and only 2 on the HBA, which ones should I connect?
• What is the difference between SAS IN, SAS IN/OUT, and SAS OUT?

And then:

• I thought (from what I have read) SAS can "split" into 4 SATA connectors or some such. So if there's only 3 mini-sas connectors per backplane, how is this supposed to be able to connect 24 drives? I assume I would need another HBA? And still I'm not sure how exactly all this comes together.

 

(the backplane connectors can be seen on page 15 of the attached manual)

If anyone could point me in the right direction and/or explain how SAS connections work, I would greatly appreciate it. I have searched this topic up and down and haven't been able to find quite the right information needed in order to completely understand. So far all I know is that SATA can be plugged into SAS controllers (or something along those lines) but not the other way around.

Manual_6Gbps 24-port expander backplane(80H10024001A0)_V1.0.pdf

[Electronics Wizardy]

21 minutes ago, dbm said:

I am assuming that I must somehow connect the SFF-8643 ports on the HBA to the backplane, is this correct?

Yes, connect the hba to the backplane search for a cable with the right connectors.

 

22 minutes ago, dbm said:

If so, since there are 3 connectors on the backplane and only 2 on the HBA, which ones should I connect?

Connect it to the inputs, so the in and the in/out

 

22 minutes ago, dbm said:

What is the difference between SAS IN, SAS IN/OUT, and SAS OUT?

Out is for daisy chaning, so you can daisy chain backplanes, that would connect the 2 backplanes together if you don't want to use as many ports on a raid card or hba

 

Change the dip switches to change the ports from in to uot

 

25 minutes ago, dbm said:

thought (from what I have read) SAS can "split" into 4 SATA connectors or some such. So if there's only 3 mini-sas connectors per backplane, how is this supposed to be able to connect 24 drives? I assume I would need another HBA? And still I'm not sure how exactly all this comes together.

That back plane has a sas expander, so it splits the sas channels to all the drives. Each of those big sas connectors on a hba/back plane has 4 channels, and the drives use one each.

 

thought (from what I have read) SAS can "split" into 4 SATA connectors or some such. So if there's only 3 mini-sas connectors per backplane, how is this supposed to be able to connect 24 drives? I assume I would need another HBA? And still I'm not sure how exactly all this comes together.

[dbm]

Thank you so much for the prompt response and explanations! I'll try this after work then.

[Jarsky]

11 hours ago, Electronics Wizardy said:

thought (from what I have read) SAS can "split" into 4 SATA connectors or some such. So if there's only 3 mini-sas connectors per backplane, how is this supposed to be able to connect 24 drives? I assume I would need another HBA? And still I'm not sure how exactly all this comes together.

Yup SAS is an addressable protocol, in that each connected device has a unique SAS address. It has a 16-bit address bus, so you can effectively daisy chain up to 65,535 devices through expanders. 

 

As Electonics Wizardy pointed out, seems it has some sort of built in expander in the backplane. 

 

[dbm]

Ah ok, cool. Good to know, thanks!