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A comment on Retrospective from Postmark on outages (MongoDB). Parent comment

Re:Retrospective from Postmark on outages (MongoDB) by willvarfar on Saturday March 31, 2012 @04:57PM (#3781516)
As I remember it:

The journaling is only fsynced every so-often - its not like it magically gives you anything like the D in ACID.

This leaves you relying on replication for durability.

And everyone has problems when they lose one of the cluster.

Luckily it wasn't the lot: http://blog.empathybox.com/post/19574936361/getting-real-abo...

I would love to be corrected; we'd all sleep easier.

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Re:Retrospective from Postmark on outages (MongoDB) by rogerbinns on Saturday March 31, 2012 @06:13PM (#3781719)
How about the actual facts:

http://www.mongodb.org/display/DOCS/Journaling

So yes it is periodic by default (in the millisecond range). However you can wait on any request until it has become durable.

As for replication, people seem to have some hate for that, but the reality is that a journalled system that has failed (any database/operating system) will take a large amount of time to come back up, replay/recover journals etc. Not that useful.

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