Hi There,

We using Mongo DB 3.2.6 to store log information, and store the log in db by its persistent time. After we drop the expired database, the database will not show by command "show dbs". The database folder size is zero, and it is still exist on the disk.
Why the db.dropDatabase() cannot purge the zero folder on the disk?

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106M diagnostic.data
300M journal
72K local
64K _mdb_catalog.wt
4.0K mongod.lock
84K sizeStorer.wt
4.0K storage.bson
0 TrackingLogDB_2016121700_2017031700
0 TrackingLogDB_2016121800_2017031800
0 TrackingLogDB_2016121900_2017031900
0 TrackingLogDB_2016122000_2017032000
0 TrackingLogDB_2016122100_2017032100
0 TrackingLogDB_2016122200_2017032200
0 TrackingLogDB_2016122300_2017032300
0 TrackingLogDB_2016122400_2017032400
0 TrackingLogDB_2016122500_2017032500
0 TrackingLogDB_2016122600_2017032600
0 TrackingLogDB_2016122700_2017032700
0 TrackingLogDB_2016122800_2017032800
0 TrackingLogDB_2016122900_2017032900
0 TrackingLogDB_2016123000_2017033000
0 TrackingLogDB_2016123100_2017033100
0 TrackingLogDB_2017010100_2017040100
0 TrackingLogDB_2017010200_2017040200
0 TrackingLogDB_2017010300_2017040300
0 TrackingLogDB_2017010400_2017040400
3.7M TrackingLogDB_2017010500_2017040500
3.7M TrackingLogDB_2017010600_2017040600
3.7M TrackingLogDB_2017010700_2017040700
3.6M TrackingLogDB_2017010800_2017040800
3.5M TrackingLogDB_2017010900_2017040900
========================

Regards
Eric Huang