[rabbitmq-discuss] Does SSD improve rabbitmq's performance

[Matthias Radestock]

Graeme,

On 20/11/13 19:50, Graeme N wrote:
> Well, the docs do explicitly say "You almost certainly should not
> change this." Given the lack of stability we've seen with persistent
> queues so far, we've definitely shied away from touching anything the
> docs say not to, for fear of increasing stability problems.

Fair enough, though note that your problems were with mirrored queues,
not the persistence mechanisms. Very few bugs have been found in the
persister in the last few years.

> Do you have further guidance on this option that's not present in the
> docs about why you would/wouldn't change this option?

The main reason for the disclaimer is the difficulty in explaining when 
one would want to change that value and what impact doing so might have.

But if you believe that the default msg_store file size is hurting
performance significantly, then experimenting with different values is
definitely worthwhile. Let us know what you find. Perhaps then we can
give some better guidance to our users than "don't touch this".

> is this safe to increase on active clusters which already have a lot
> of data in existing files?

That should be safe.

Matthias.