I am wondering whether the HBase cachingHitRatio metrics that the region
server UI shows, can get me a break down by data blocks. I always see this
number to be very high and that could be exagerated by the fact that each
lookup hits the index blocks and bloom filter blocks in the block cache
before retrieving the data block. This could be artificially bloating up
the cache hit ratio.

Assuming the above is correct, do we already have a cache hit ratio for
data blocks alone which is more obscure ? If not, my sense is that it would
be pretty valuable to add one. Thoughts ?