First thing is you're going to want to set up an ISO share so you can start launching VMs. I set up a CIFS share so that I can just put ISOs into a folder on my workstation and have XenCenter automatically be able to mount them.
I don't want this on my workstation. Does XenServer not have a method to locally store files someplace?
With Hyper-V I can just drop iso files in a folder on the C/D/E/Whatever drive.
With VMWare I can upload iso files to a folder on the the datastore.
As @DustinB3403 linked you have to add it from cli through the Dom0. Kind of stupid if you ask me.
May be kinda stupid, but considering they have a Dom0, kinda makes sense. It's the same in Hyper-V. ESXi is the odd-man out here, but then, there's no Dom0 there.
I understand since the Dom0 doesn't have much room, but they should give you the option to mount a usb through XenCenter though.
They don't, I believe, because they want the XC interface to be easy for people working with pool, which is the majority of their base. Using a USB drive on a single host makes a lot of sense when you have only one host but when you have a lot of them it would potentially get really confusing.