I recently enabled jumbo frames on my SG200 to experiment a bit and see how they work.  Before I started I made sure I was at the latest firmware which I believe is 1.4.0.88 at the moment.  My environment consists of an SG200 28 port switch.  A Dell server running Windows 2012 using 2 port LAG with LACP and a Synology NAS also using 2 port LAG with LACP and using latest OS.  The Dell has two options for jumbo ports.  I can pick from 4088 or 9014.  The Synlogy lets me pick from 2000, 3000 all the way to 9000 MTU size. 

Test #1: Set both Dell NICs for 4088 size (Team NIC does not have MTU option) and then set Synology for 4000 MTU (Synlogy is the opposite of Dell with MTU setting on the team and individual NIC settings not available).  With this setup jumbo frames did not seem to work at all as tested using ICMP with -l and -f flags.  Not sure if this means anything but I did not get the "packet needs to be fragmented" message at all.  Pings basically just failed.   I progressively changed the Synology to 5000,6000,7000,8000 and 9000 and was never able to get a large packet ping.  Why is this?  Any ideas?

Test #2: Set Dell for 9014 and Synology for 9000 and then I can get up to 8890 size packets to ping.  So far so good. However, now the disappointing news.  Performance did not seem to be affected not one iota.  Before the jumbo frames Windows would report transfer averaging about 60MB/s with some peaks going all the way to 110MB/s.  After the 9000 jumbo frames the file copies were virtually identical.  I did these tests with 20GB+ VHD files.  Any ideas?

Thanks,

Diego