This issue is only affecting XenServer 7 (no problem on earlier version).
It seems that RRDs reporting `io_read_kbs` and `io_write_kbs` are going mad.
With XE, I got:
io_read_kbs ( RO): 656288.750
io_write_kbs ( RO): 656288.750
Which is obviously not the case for real (my SR can't be at this speed)
Graphing this stuff in XenCenter or Xen Orchestra confirm this strange behavior:
On last 10 minutes: