[rabbitmq-discuss] Write to Disk policy of RabbitMQ

Wed Sep 1 07:39:00 BST 2010

Abhishek,

Abhishek Kona wrote:
> I am using RabbitMQ with all durable queues and persistent messages. 
> What is the write to disk policies of RabbitMQ, does it do a disk 
> operation for the persistent messages on each operation on the queues or 
> it does a write to disk in once in n amount of time.

Neither :) There is a lot of caching, buffering, coalescing and various 
other optimisations going on.

Rabbit guarantees that data relating to persistent messages in durable 
queues will be written to disk *eventually* if a) that's actually 
necessary (e.g. the message hasn't been delivered and ack'ed already), 
and b) nothing disastrous happens to the broker.

The guarantee is strengthened when using tx. On receipt of a 
tx.commit-ok all the actions on persistent messages in durable queues 
are guaranteed to have been written to disk if necessary.

> What is the exact policy.

Matthew might explain some of the details in a blog post one day.

Regards,

Matthias.