Xserve HD Backplane Card (third PCIe?)

[osxster]

Hello,

I have been wondering this and curious if anyone had any thought on this. Right now on the Xserve, there are only 2 PCIe slots on it. So you are restricted on the number of cards and thus if you wanted to do 10GBE, an external RAID controller, you have no slots left. Given there is a RAID controller which you can also replace with a nonRAID controller, how is this hooked up to the motherboard? Is this a secret PCIe interface that could be used for an external PCIe card? I'd love to have 10GBE without losing one of my slots. Anyone have any thoughts on this?

O.

 

[reukiodo]

Doesn't synology now offer a 10Gb+NVMe combo card? What other card do you want to use?

I believe the 2009 Xserve has an MXM slot which is based on PCIe, so maybe tbat could be repurposed?

 

[osxster]

Ideally what I'd like to do is using this as a gaming server running ESXi. I'd want to move my existing NetApp DS4246 shelf from my Mac Mini over to it, run 10GBe and be able to have two video cards on it for GPU Pass thru. I successfully am able to run ESXi 6.5 on it with GPU Pass Thru. But I'd like to have two GPU cards in it and also an external SAS expander with maybe 10GBe. Perhaps the MXM slot is an idea as I removed that video card to get my AMD card working. If someone had a combo JBOD SAS controller with 10GBe that might be an option and use the MXM slot.. I guess I am asking for a lot out of my Xserve! With the 10GBe support I could connect a second Xserve and share the drives via iSCSI. That would be a future goal if this all worked out.

 

[Ludacrisvp]

I'd look at using a Thunderbolt card (titan ridge?) with a eGPU style setup in the xserve.
Or get an external PCIe expansion chassis.
I've never seen MXM to PCIe, only PCIe card with MXM slots on them, not sure that is the solution for you.

the LSI controller is likely on a proprietary connection to the board.

 

[aaronb1]

Yes, the RAID or SATA backplane is connected via a PCIe 2.0 x4 link directly to the I/O Hub. So, between the two x16 PCIe slots, and this x4, that uses up all 36 PCIe lanes offered by this generation of XEON CPU/Chipset.
The MXM slot has a PCIe 1.0 x2 link to the I/O Contoller (a.k.a. Southbridge), not directly to CPU. It is only x2 width, and Gen 1 (2.5 Gbps) speed, plus it shares bandwidth with everything else connected to the I/O Controller, including the two GbE ports. This significantly restricts the bandwidth available to any card on the MXM. I wouldn't put my primary video on there for sure.

I have meant to map out the connections on that link but haven't gotten around to it yet. Connecting a generic PCIe card should be possible in theory. It is possible however that the BootROM will refuse to configure an unknown device on that link (in the same way that HP laptops might refuse to use generic mini-PCIe cards in the "WiFi" PCIe slots).

source: Xserve early 2009 technician guide, block diagram page 21.

 

[hobowankenobi]

Do you really need two RAID controllers and two separate arrays?

Why not simply go SSD on the internal SATA for boot OS (could mirror two if you wanted), and go external RAID for all storage? Simple, less heat & power draw, one less point of failure.

I ran a production Xserve like that for years, and even had a nightly clone to the third bay, so if the boot SSD (or the entire mirror) bent belly up, just boot to the third drive and keep on truckin'. Areca RAID controller and a fat external array ensured massive space and throughput. The Areca card had two ports, so you could still run 2 external RAIDs if needed.