On our system , today for instance, we average WAITIO of24% with an average BUSY of 44%. At somepoints as overall usage goes up, all the IDLE time is effectively IOWAIT. Does this seem overley high? or would you think it depends on the site, and whats normal for them?
I just checked it, according to the recommendations CPUIoWait should be even less than 10% when the system is 100% busy. But this was some years ago before the new Linux system, i don't know if this changed. Nevertheless you should ask your friendly Teradata support people about that.
Btw, CPUIoWait might be Bynet, too, not only disks.