MTU Sizes Jumbo Frames

Hi all,

I have an N2048 switch that has a Global MTU setting at 1518.  But the Max Frame size on my Port configuration is showing 9216.  Of all our switches, this is the only switch with a Max Frame Size of 9216.  All other switches (including my core) all show the max as 1518.  This switch is my server switch.  This switch is linked to our core.  I have a problem with one of my AS400 cloud backups taking an extremely long time to backup.  I'm wondering if this setting could contribute to that slowness?  Prior to me coming into this position, all parties involved in this cloud backups could not find out why it was running so slow so the indication is that the problem was within our network.  If this could be the cause, how do you turn off Jumbo frames and what impact could I see from doing that?  thank you..