Hi
DRE cache is used in the process of optimization. Hence you want your DRE cache to be utilized to the maximum extent.
Seeing DRE cache utilization at 98% is correct. After that level, any stale cache will go through an eviction process.
If you see 99% utilization then there is a problem - a memory upgrade procedure has not been followed correctly would be my diagnosis.
So the behavior you are seeing - which is DRE cache filling up is normal.
Regards
Rama