Here you can see the exam objective:
IBM: Test 000-221: AIX 7 Administration
I don't think there's any RedBook specifically for AIX 7. But you can follow RedBooks sg246191, sg247940, sg247965, redp4815 for AIX 6 administration plus PowerVM. RedBook sg247910 is the differences guide from earlier version of AIX to AIX 7.
For Blade hardware check out this link:
IBM Redbooks | BladeCenter
If you have worked on UNIX platforms, you will do fine for basic administration tasks. 2-3 years of experience on AIX/Power system is recommended before taking the IBM certification as you need to know the hardware very well.
Best of luck!