MongoDB server on Ubuntu, doesn't send acknowledgment on insert -

using ubuntu mongodb server (mongo version 3.0.4, ubuntu - 14). of inserts never return acknowledgment. reason that, , how can fixed? document written db collection. happens on ~1/10,000 documents.

mongodb provides different levels of write concern better address specific needs of applications. clients may adjust write concern ensure important operations persist entire mongodb deployment.

for other less critical operations, clients can adjust write concern ensure faster performance rather ensure persistence entire deployment.

http://docs.mongodb.org/manual/reference/write-concern/

if want ensure receive acknowledgment on insert can put w param > 1 or "majority" (enough in cases).

important: if set w number greater number of set members hold data, mongodb waits non-existent members become available, means mongodb blocks indefinitely.