Hi Tom,
Below parameters may help to reduce the compaction number:
<property>
<name>hbase.hstore.compactionThreshold</name>
<value>3</value>
<description>
If more than this number of HStoreFiles in any one HStore
(one HStoreFile is written per flush of memstore) then a compaction
is run to rewrite all HStoreFiles files as one. Larger numbers
put off compaction but when it runs, it takes longer to complete.
</description>
</property>
Make the value larger, if there are too many small files in the region dir,
this may help a lot.
Frank Chow