In our Journal documentation it doesn't mention that turning off journaling will result in performance issues for WT.

There are a couple of issues as I understand it. One I think I understand well:

• If using j : true or w : "majority", writes can't be acknowledged until they make it to disk. Therefore, any time a write comes in, a checkpoint is triggered in order to persist the data quickly and acknowledge the write. The performance cost of frequent checkpoints, however, is far in excess of the performance benefits of turning off journaling for most production systems.

The other I am less sure about:

• I think I've heard a rumor that even without j : true there are still performance costs of turning off the journal.

anonymous.user do you know any details about this? Have anything to add? Alternatively, have I misunderstood the part about performance impacts without journaling?