Cisco UCS MTU Sizing with VIC

So, in my last article, I discussed Appliance Ports and how to set them up. But there was a hidden gem in there that I felt deserves its own article because it’s just that cool. If you’ve ever setup the MTU on servers because you want to use an iSCSI array, you’ve suffered through how exactly to get the OS to recognize the new MTU size. As I pointed out in my last article, this process this involves a registry hack, ifconfig, esxcfg-vswitch, or setting the MTU manually within the Windows adapter properties. It’s worth the time to investigate because many applications perform better when the conversation doesn’t have to be fragmented into many small chunks. Continue reading

Appliance Ports in Cisco UCS

So, I recently had a customer that wanted to enable “Jumbo Frames” to a UCS server that had the Cisco Virtual Interface Card (VIC) installed in it (also applies to Palo/M81KR, VIC-1240, VIC-1280). You might also know this process as “maximizing the MTU”. In this particular situation, the customer had an iSCSI appliance directly connected to the fabric interconnects (Whiptail in this case, which is not officially supported by Cisco as of this writing, but this process will be the same for any iSCSI appliance – supported or unsupported). It’s not the first time this has come up so I thought I’d write it down so that everyone can benefit (including me when I forget how I did all of this). This article will be helpful if you’re using any NAS storage such as NFS, CIFS/SMB, or iSCSI. Continue reading