in hbase 0.98.10, if we use LruBlockCache, and set regionServer's max heap to 10G in default: the size of in_memory priority of LruBlockCache is : 10G * 0.4 * 0.25 = 1G
0.4: hfile.block.cache.size 0.25: hbase.lru.blockcache.memory.percentage if we do not set any user tables IN_MEMORY to true, then the whole hbase just need to cache hbase:meta data to in_memory LruBlockCache. hbase:meta does not split , so just need one regionServer to cache, so there is some waste in blockCache i think the regionServer open hbase:meta need to set in_memory LruBlockCache to a certain size other regionServer set hbase.lru.blockcache.memory.percentage to 0, do not need to allocate in_memory LruBlockCache.
