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From Harsh J <ha...@cloudera.com>
Subject Re: Swap requirements
Date Wed, 25 Mar 2015 22:28:11 GMT
The suggestion (regarding swappiness) is not for disabling swap as much as
it is to 'not using swap (until really necessary)'. When you run a constant
memory-consuming service such as HBase you'd ideally want the RAM to serve
up as much as it can, which setting that swappiness value helps do (the OS
otherwise begins swapping way before its available physical RAM is nearing
full state).

The vmem-pmem ratio is something entirely else. The vmem of a process does
not mean swap space usage, just simple virtual memory used by the process.
I'd recommend disabling YARN's vmem checks on today's OSes (but keep pmem
checks on). You can read some more on this at
http://www.quora.com/Why-do-some-applications-use-significantly-more-virtual-memory-on-RHEL-6-compared-to-RHEL-5

On Thu, Mar 26, 2015 at 3:37 AM, Abdul I Mohammed <oracle.blog3@gmail.com>
wrote:

> Thanks Mith...any idea about Yarn.nodemanager.Vmem-pmem-ratio parameter...
>
> If data nodes does not require swap then what about the above parameter?
> What is that used for in yarn?




-- 
Harsh J

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