HP XP Performance Advisor Software - Manual (Page 58)

= 100*(2/2)
= 100*1
= 100
The Wr% is 100% because all the front-end I/Os on that RAID group are writes.
NOTE:
We can conclude all the front-end I/Os on the RAID group are writes because the r_H% (cache read
hit %) is 0; that is, there are no front-end reads.
Understanding write ratio in XPWatch 58