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From Toke Eskildsen ...@statsbiblioteket.dk>
Subject RE: clarification on index-to-ram ratio
Date Thu, 19 Jun 2014 18:21:24 GMT
Vinay Pothnis [pothnis@gmail.com] wrote:
> *"... Let's say that you have a Solr index size of 8GB. If your OS, Solr's
> Java heap, and all other running programs require 4GB of memory, then
> an ideal memory size for that server is at least 12GB ..."*

> So, when we say "index size" does it include ALL the replicas or just one
> of the replica? Say for example, if the solr instance had 2 replicas each
> of size 8GB, should we consider 16GB as our index size or just 8GB - for
> the above index-ram-ratio consideration?

16GB, according to the above principle. Enough RAM to hold all index data on storage.

Two things though,

1) If you have replicas of the same data on the same machine, I hope that you have them on
separate physical drives. If not, it is just wasted disk cache with no benefits.

2) The general advice is only really usable when we're either talking fairly small indexes
on spinning drives or there is a strong need for the absolute lowest latency possible. As
soon as we scale up and do not have copious amounts of money, solid state drives provides
much better bang for the buck than a spinning drives + RAM combination.

- Toke Eskildsen

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