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From Walter Underwood <wun...@wunderwood.org>
Subject Re: Pressed optimize and now SOLR is not indexing while optimize is going on
Date Wed, 07 Oct 2015 15:44:32 GMT
Unix has a “buffer cache”, often called a file cache. This chapter discusses the Linux
buffer cache, which is very similar to other Unix implementations. Essentially, all unused
RAM is used to make disk access faster.

http://www.tldp.org/LDP/sag/html/buffer-cache.html <http://www.tldp.org/LDP/sag/html/buffer-cache.html>

wunder
Walter Underwood
wunder@wunderwood.org
http://observer.wunderwood.org/  (my blog)

> On Oct 7, 2015, at 3:40 AM, Toke Eskildsen <te@statsbiblioteket.dk> wrote:
> 
> On Wed, 2015-10-07 at 07:03 -0300, Eric Torti wrote:
>> I'm sorry to diverge this thread a little bit. But could please point me to
>> resources that explain deeply how this process of OS using the non-java
>> memory to cache index data?
> 
> http://blog.thetaphi.de/2012/07/use-lucenes-mmapdirectory-on-64bit.html
> 
> Shawn Heisey:
>>> Whatever RAM is left over after you give 12GB to Java for Solr will be
>>> used automatically by the operating system to cache index data on the
>>> disk.  Solr is completely reliant on that caching for good performance.
>> 
>> I'm puzzled as to why the physical memory of solr's host machine is always
>> used up and I think some resources on that would help me understand it.
> 
> It is not used up as such: Add "Disk cache" and "Free space" (or
> whatever your monitoring tool calls them) and you will have the amount
> of memory available for new processes. If you start a new and
> memory-hungry process, it will take the memory from the free pool first,
> then from the disk cache.
> 
> 
> - Toke Eskildsen, State and University Library, Denmark
> 
> 


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