As kimchy answered, the real problem is that solitary nodes which hold no shards and are not master do not help much.
The only motivations would be - move out HTTP connection management, e.g. when clients are slow and appear in masses. The hardware requirement are low as long as the network bandwidth is ok and there are lot of sockets/ file descriptors available. - running spare nodes instead of HTTP load balancing in nginx e.g. (nginx is better in doing this) When clients demand huge data sets from such nodes, there might be some load on them regarding result aggregation but that is not a real problem in comparison to the heavy duty nodes that hold the shards. The real load is where the shards are. Jörg On Tue, Nov 18, 2014 at 9:59 PM, Lasse Schou <[email protected]> wrote: > Thanks! > > And yes I do actually have 3 master nodes! > > I was hoping to learn more about the requirements of the client nodes (for > querying only). What work is actually performed by them? Simply querying > the data nodes and merging the results, or is more heavy-weight > in-memory aggregation and sorting done of those nodes that need RAM and CPU > power? > > Den tirsdag den 18. november 2014 skrev Mark Walkom <[email protected] > >: > >> You should really use 3 master nodes if you have a lot of data nodes, >> having 3 makes getting a quorum a lot easier. >> >> I've previously run master nodes with 2 vcpus, 8GB RAM (4 heap) and 40 >> odd data nodes, with sporadic querying and had no issues at all. Ultimately >> it depends on your use case, but if you are having gains using your current >> setup, then it makes sense to increase the hardware capabilities of what >> you have and compare this to the previous setup, then make a call. >> >> On 18 November 2014 23:11, Lasse Schou <[email protected]> wrote: >> >>> Hi, >>> >>> There is an excellent question asked about two years ago that was never >>> properly answered: >>> https://groups.google.com/forum/#!topic/elasticsearch/dxjpMd4vNXQ >>> >>> I have the exact same question. I've got a cluster with a lot of data >>> nodes plus two nodes that act as master + client nodes (no data). >>> >>> For now I'm using those two nodes for both master (shard/cluster >>> management) tasks and client tasks (query handling). >>> >>> I've seen a big performance gain when querying the client nodes, >>> compared to querying my very busy data nodes directly. >>> >>> But I'd still like to get your view on the hardware requirements of the >>> master/client nodes. Is RAM important for serving the query results, or is >>> most RAM-heavy tasks performed by the data nodes? And similarly, is CPU >>> important on the client nodes? >>> >>> Thanks, >>> Lasse >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "elasticsearch" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/elasticsearch/35d4a8c8-755c-4f7b-80ef-eab9e0f85d08%40googlegroups.com >>> <https://groups.google.com/d/msgid/elasticsearch/35d4a8c8-755c-4f7b-80ef-eab9e0f85d08%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> You received this message because you are subscribed to a topic in the >> Google Groups "elasticsearch" group. >> To unsubscribe from this topic, visit >> https://groups.google.com/d/topic/elasticsearch/0mYiJMAblwU/unsubscribe. >> To unsubscribe from this group and all its topics, send an email to >> [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/elasticsearch/CAF3ZnZmVq7mesOC0NkpX1sbrnB0VJguo4G3WtWBWbUPSsna_xw%40mail.gmail.com >> <https://groups.google.com/d/msgid/elasticsearch/CAF3ZnZmVq7mesOC0NkpX1sbrnB0VJguo4G3WtWBWbUPSsna_xw%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > -- > You received this message because you are subscribed to the Google Groups > "elasticsearch" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elasticsearch/CADERWXpG%3DZD_NWmk2STJmZUVA_fCeiY1Va%2BWm-50Gh7GXbCqUw%40mail.gmail.com > <https://groups.google.com/d/msgid/elasticsearch/CADERWXpG%3DZD_NWmk2STJmZUVA_fCeiY1Va%2BWm-50Gh7GXbCqUw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "elasticsearch" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/elasticsearch/CAKdsXoECjKoKF015j24-JEv%2B9qtXanu_MZiOgi-mE7dkU5YeRw%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
