We have noticed this issue where data that is being "safely" written to the database, is not available few seconds later (say 2 seconds). Basically we do some safe writes to a collection (inside a web worker/request) and expect that data to be available from another process (Sidekiq workers).

I understand this could be a MongoDB or Mongo driver issue, but wanted to know if anyone has seen similar behavior?

Ours is a Rails 3.2.9/Ruby 1.9.3/Mongo 2.0.4 application.

Here's how we doing safe writes:

account.safely.save!

Also, sharding is enabled for this collection and there is significant load on the server.

Following are the gems we use:

gem 'mongo', '1.6.1'
gem 'mongoid', '2.4.10'