Durability issue: lost set after 3-4 days

Couple of questions. Was the entire server rebooted? How did you cleanup the existing sets? I also noticed that there was no default-ttl set in your config which would default to 0 meaning never expire.

Basically what may be happening is older data that were on disk being re-indexed into memory as part of a cold-start. Please see the following article for ore info:

For your particular case, you may need delete /opt/aerospike/test.dat prior to loading new test data.