[rabbitmq-discuss] Write to Disk policy of RabbitMQ
matthias at rabbitmq.com
Wed Sep 1 07:39:00 BST 2010
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.
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