For some information about the AX100i, check the Dell|EMC AX100 support site here.

Keep in mind that the AX100i is not a NAS box. You have to use either a Qlogic 4010 HBA or an iSCSI initiator software package to turn one of your (Gbit) NICs into an iSCSI connection. Drives will show up as a local drive, not a network share. This also means you cannot share disk space between multiple systems, unless they are clustered. You can however connect multiple systems, each with their own storage space.

Yes. I have 2 AX100i's in production. One as File Storage and one as off-site Backup. I have a dedicated iSCSI network that the SANs and Servers are connected to. I am using a mixture of HBA's and Nics w/initiator software. To get better performance i would like to enable Jumbo Frames on the Server Nics and the dedicated iSCSI Switch which all have the capability. I don't see the option in the AX100i settings and can't find any real specs on the AX100i iSCSI Nics to see if they support Jumbo Frames.

I found an article here that says "Dell claims that the next revision of the AX100i will include jumbo-frame support. That should bring a significant performance boost to this array." However i don't see anything in the release notes for the firmware versions.

The AX100i does not support jumbo frames and it will not support them in the future.
(no matter what the article says)