Mathias Meyer

It's true, we also experienced data loss (several millions of log data caused by dirty shutdown, it's data file is very fragile) issue like this thread http://groups.google.com/group/mongodb-user/browse_thread/thread/d0111a47984cb688

I found the following two posts very insightful：

1, http://www.mikealrogers.com/2010/07/mongodb-performance-durability/

"This (mongodb's write plolicy) is kind of like using UDP for data that you care about getting somewhere, it’s theoretically faster but the importance of making sure your data gets somewhere and is accessible is almost always more important."

2, http://www.paperplanes.de/2011/1/10/mongodb_and_data_durability.html

"It's okay to accept trade-offs with whatever database you choose to your own liking. However, in my opinion, the potential of losing all your data when you use kill -9 to stop it should not be one of them, nor should accepting that you always need a slave to achieve any level of durability. The problem is less with the fact that it's MongoDB's current way of doing persistence, it's with people implying that it's a seemingly good choice. I don't accept it as such."

I can't see using MongoDB for any production project. It combines a limited replication/sharding model with a poor single-server durability, lack of tunable CAP constraints, and some surprising performance bottlenecks.

If you want integrity and SQL, use PostGres. If you want volatile speed, use Redis or Membase. If you want a rich data model and excellent durability with limited but highly configurable replication, experiment with Couch. If you want federation, predictable horizontal scaling, and HA, perhaps look at Voldemort, Cassandra, HBase, or Riak. There are a lot of good datastores out there, and chances are one of them fits your needs better.

Edit: I think http://www.paperplanes.de/2011/1/10/mongodb_and_data_durability.html basically sums it up. When the Mongo folks started telling me that kill -9 should never happen to any database, I stopped taking them seriously.

42 floors has an interesting mandatory 2 weeks vacation when you start working there. [0]

Paperplanes has a mandatory minimum vacation policy on top of their unlimited vacation policy, in order to prevent employees from feeling like they can never take a break since there's always more to do (a common issue with unlimited vacation policies).

As for my own startup, we're still super early stage so its "unlimited" but I don't foresee us being able to take a break anytime soon. :/

[0]: http://www.businessinsider.com.au/42-floors-vacation-policy-2013-4
[1]: http://www.paperplanes.de/2014/12/10/from-open-to-minimum-vacation-policy.html