The only issue is whether or not you are using Storage Link.  If so then, you can't upgrade.  Citrix wrote, and certifies SL.   The last validated branch was 5.2.x.   If on the other hand you are using LVM over iSCSI aka Software iSCSI initiator then you can upgrade to 7.0.5.  You will have to upgrade to 6.0.10 first, before going to 7.0.5.    MPIO is not a factor either way.   Citrix has provided patches for 6.0.x, and 6.1.x to support it. MPIO works with Storage Link and plain iSCSI adapter.  This PDF has instructions on how to configure MPIO and a link to the patches from Citrix.   en.community.dell.com/.../download.aspx XS 6.2 comes with the patches already included.   Regards, 
Hi Group, Are there any gotcha's to look out for here. The customer has ZEN 6.1 and the array firmware is old at 5.2.5. They want to go to 7.0.5, the ZEN can't be upgraded. There is no multipath configured from what I can see. Thanks in advance.
Firmware update from 5.2.5 to 7.0.5 with XEN 6.1