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

Wed Nov 20 19:50:30 GMT 2013

On Wed, Nov 20, 2013 at 11:41 AM, Matthias Radestock
<matthias at rabbitmq.com>wrote:

> On 20/11/13 19:10, Graeme N wrote:
>
>> Looking at the files under
>> /var/lib/rabbitmq/mnesia/rabbit at hostname/msg_store_persistent on our
>> busiest host, and we see ~390 files, all <= 17 MiB. Compare to MySQL or
>> Riak, where we split the InnoDB or Bitcask append-only logs at 500 MiB,
>> which is chosen so it fits inside of our hardware RAID controllers' BBU
>> caches.
>>
>
> The msg_store file size is configurable. See msg_store_file_size_limit at
> http://www.rabbitmq.com/configure.html#config-items. If you want to set
> that to 500MiB, go for it.
>

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. Do you have further guidance
on this option that's not present in the docs about why you would/wouldn't
change this option? For instance, is this safe to increase on active
clusters which already have a lot of data in existing files?

Graeme
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