[rabbitmq-discuss] vm_memory_high_watermark of RabbitMQ

Thu Aug 2 14:57:28 BST 2012

Hi,

On 02/08/12 04:15, Chen, Bin wrote:
> Be default, "vm_memory_high_watermark" is set to 800 MB.
> Based on the document, this means the fraction is 0.4.

Actually it's the other way around. The default is 0.4, which means that
the total RAM detected on your system is 2Gb. Confirm with
rabbitmqctl eval 'erlang:memory().'
or "rabbitmqctl status" as you have done.

> My system is Windows 2008 Server 64-bit. It has 24 GB ram installed.

That's alot more than the 32bit version of Erlang can address.

> When I ran "rabbitmqctl status", I got a different fraction for
> "vm_memory_high_watermark".

The fraction should still be 0.4, and I would expect the watermark to be
about 10Gb, provided the maximum RAM is detected correctly and you are
using the 64bit version of Erlang.

> It is much smaller than 0.4, and it seems equal to 800 MB / 24 GB.

Can you please provide the output of
rabbitmqctl eval 'os_mon_sysinfo:get_mem_info().'
It may be that the total memory rather than the total addressable memory
is being used. You should consider using the 64bit version of Erlang though.

-Emile