SOLVED Supermicro sideband connection between backplane and MB

[Juliean]

A bit esoteric, but perhaps someone can help out. I am building a server that uses a Supermicro X11SCL-F motherboard in an older 825TW-R700LPB chassis. The chassis contains a BPN-SAS-825TQ backplane.

I'm trying to figure out if it's necessary/desirable/possible to connect the backplane's sideband connector to the MB. The MB manual (https://www.supermicro.com/manuals/motherboard/X11/MNL-2063.pdf) p 47 describes a pair of SGPIO headers and states "The SGPIO headers are used to communicate with the enclosure management chip on the back panel. "

The chassis manual (https://www.supermicro.com/manuals/chassis/2U/SC825.pdf) p. B-5 states " The sideband headers are designated JP51 and JP52. For SES-2 to work properly, you must connect an 8-pin sideband cable. See the table to the right for pin definitions" and then p. B-7 says "This backplane can utilize SGPIO or I2C, which is the default mode and can be used without making changes to your jumpers. The following information describes which jumper must be configured to use SGPIO mode."

So it looks to me like I'd need to set the backplane to SGPIO mode, and then these would be connectable, but the pinouts don't seem to match at all. Is the "8-pin sideband cable" a specific cable for this purpose? Do I need to try to figure out the pinout mismatch and make my own cable (I can do it, but that seems.... odd to make my own cables).

More fundamentally, what purpose does this sideband connection serve? I saw in the FreeNAS manual, section 9.3 the following: "Beginning with version 9.2.1, FreeNAS® provides a graphical screen for configuring an IPMI interface. This screen will only appear if the system hardware includes a Baseboard Management Controller (BMC). " Is this connection required for the IPMI screen to work? In any event, Is this all necessary? Will it benefit me in some way? Should I just skip it?

If it matters, the machine will be a pure NAS, running FreeNAS on bare metal, no jails, no VMs living on the machine, just pure data storage.

Thanks!

 

[Ericloewe]

You need the sideband basically to control the LEDs. Some breakout cables include the connector, but you'll need something separate if you're connecting SATA-style ports to a TQ backplane.

I saw in the FreeNAS manual, section 9.3 the following: "Beginning with version 9.2.1, FreeNAS® provides a graphical screen for configuring an IPMI interface. This screen will only appear if the system hardware includes a Baseboard Management Controller (BMC). " Is this connection required for the IPMI screen to work?

It has nothing to do with IPMI, although monitoring could conceivably be provided via IPMI, Supermicro doesn't do that.

 

[Juliean]

You need the sideband basically to control the LEDs. Some breakout cables include the connector, but you'll need something separate if you're connecting SATA-style ports to a TQ backplane.

I'm not sure I understand. My setup has an HBA card that connects to the backplane via a pair of 1-to-4 SFF to SATA cables, and the drives are SATA drives that plug into the backplane via the hotswap bays of the chassis. Are you talking about the "drive active" LEDs on each bay? I thought those were controlled directly by the backplane? Or is this about the "hdd" LED on the front control panel? If that's the only thing I would lose, I'm perfectly ok with that...

 

[Ericloewe]

My setup has an HBA card that connects to the backplane via a pair of 1-to-4 SFF to SATA cables

Oh, I figured you'd be using motherboard SATA. In that case, an SFF-8087/8643 breakout cable with the sideband cable hanging off it would work nicely.

Are you talking about the "drive active" LEDs on each bay?

Yes, and they're more than that. They're controllable to a certain extent using SES. Very useful for indicating disks that you want to identify, e.g. sesutil locate da12.
I believe basic access LED functionality is available without the sideband being active, but I remember something like it operating in reverse (off for access), according to people who tried it.

Or is this about the "hdd" LED on the front control panel? If that's the only thing I would lose, I'm perfectly ok with that...

Those are part of the front panel header, along with power, reset, etc.

 

[Juliean]

Ah, got it. I'd bought some generic SFF-SATA cables, but I now see the Supermicro branded ones that have the sideband. Cheap enough that it was worth ordering a pair.

Thanks!