On 2/22/2018 10:45 AM, LOPEZ-CORTES Mariano-ext wrote:
For the moment, I have the following information:

12GB is max java heap. Total memory i don't know. No direct access to host.

2 replicas =
        Size 1 = 11.51 GB
        Size 2 = 11.82 GB
(Sizes showed in the Core-Overview admin gui)

OK, so you have about 23GB of total index data on the machine.  With a 12GB heap, and assuming there's no other software running on the machine, then for good performance I would want to have at least 32GB total memory, which leaves around 20GB for the OS to cache the 23GB index.  More memory would be better, but probably isn't a requirement.  If there is other software running on the machine, then that will increase the total memory requirement.

It is always possible that your Solr install is in a situation where 12GB of heap is actually not quite big enough. If that happens, performance will usually be a lot worse than in situations where the left-over memory is not enough for the OS to cache the index properly.

You might be able to get decent performance if the total memory is about 24GB, but that much might NOT be enough.  There are a lot of factors affecting actual memory requirements.

The Solr admin UI will tell you what the total physical memory in the system is, on the dashboard.  It will be the upper right graph.  Note that this graph is likely to show 100% or nearly 100% full.  Don't let this alarm you -- it's normal.

How did you arrive at the 12GB size for your heap?  Have you tried reducing this number so that there is more memory left for the OS to handle disk caching?  I have no idea whether your Solr install will still work properly with a smaller heap, so be aware that reducing the heap might cause more problems.



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