Hi all, wanted to report back here with this info. Just got a definitive answer from a Level-3 tech support person at DRI. The answer was “We don’t support Jumbo Frames”.
Not sure if that means they don’t “support” as in they don’t want you to turn them on if you’re having troubles, or that the hardware doesn’t actually support an MTU of 9000.
Just wanted to share the info here as I know quite a few people have asked about it and it’s unclear from the documentation and KB.
I believe the Pro DOES support MTU9K (Jumbo) but using it will be an unsupported environment. So, use it at our own risk and DRI will not talk to us but we can always help each other to make drobo a better product & BeyondRAID beyond our expectations. Speaking both reliablity & performance! Not to mention the price. 
Yes I suspect that it does physically support 9k frames as with my mac pro if I manually enable 9k frames and it can’t negotiate that with the endpoint it will revert back to MTU 1500 – which it doesn’t when my DP is attached so it should physically support it at least at the interface level.
I have my Mac mini set to 9k connected to a dlink giga switch connected to my DroboPro. I have a Macbook pro set up for 9K frames and I can say it works 100% with the drobo Pro.
I have my Mac mini set to 9k connected to a dlink giga switch connected to my DroboPro. I have a Macbook pro set up for 9K frames and I can say it works with the drobo Pro.
Please see my post for further results with Jumbo frames on
Test resuts
I have tried my Mac Mini, a Windows 2008 Server, and several flavours of Linux, each one configured with Jumbo and then again without. All of these were connected to an HP ProCurve switch and I captured all packets while each machine interacted with the DroboPro.
At no time did the Drobo Pro EVER send a packet larger than 1512 bytes.
So I would support that I have seen with my own eyes that the DP doesn’t support Jumbo Frames.
would be great if someone from DR could enlighten us. Does the Drobo Pro have jumboframes capabilities or not? if not, that might be a good feature to put on the dashboard… who runs SAN with mtu at 1500?!
No it does not. You would be using it at your own risk.