How can I stop those files from being created ?
Every 2-3 day I clear those files because they're taking place in the /var/ directory
This is NSM nightly backup and it is configured in haSvr.cfg file.
Please refer: https://kb.juniper.net/InfoCenter/index?page=content&id=KB13215 and change "highAvail.numOfBackups" from 7 to 2 or 3 and then restart haSvr service : "service haSvr restart"
After this it will take 2 or 3 (whatever you configured) backup and delete old backups.
If this worked for you please flag my post as an "Accepted Solution" so others can benefit.