We recently upgraded to a 3 node search head cluster of 8 core boxes. Our limits.conf across the cluster is:
max_searches_perc = 50
base_max_searches = 10
max_searches_per_cpu = 10
So according to some Splunk math:
max_searches_per_cpu × number of CPUs + base_max_searches = Total number of searches
10 X 8 + 10 = 90 (x 3 SHs) = 270 concurrent searches
I've recently noticed we started to have some of our scheduled jobs skipped for some unknown reason. So I started some digging and discovered via this search:
index=_internal source=*metrics.log group=searchscheduler | timechart partial=false span=1m sum(dispatched) AS Started, sum(skipped) AS Skipped by splunk_server | table _time Started*
That ALL our scheduled jobs were running on ONE search head. I assumed that with SH Clustering, these scheduled searches would be divided up across the cluster based on the load of each search head. As this is NOT the case, how can I reasonably expand the cluster to allow for our increased number of scheduled reports?
index=_internal source=*metrics.log group=searchscheduler | timechart partial=false span=1m sum(dispatched) AS Started, sum(skipped) AS Skipped by splunk_server | table _time Started*
DISPATCHED --> in my opinion dispatched are always from CAPTAIN. You will have a better idea if you do this:
index=_internal sourcetype=splunkd component=Metrics group=searchscheduler host=splunksearchhead* | timechart span=1h sum(completed), sum(skipped) by host
and then see if the searches are getting distributed properly across search heads.
index=_internal source=*metrics.log group=searchscheduler | timechart partial=false span=1m sum(dispatched) AS Started, sum(skipped) AS Skipped by splunk_server | table _time Started*
DISPATCHED --> in my opinion dispatched are always from CAPTAIN. You will have a better idea if you do this:
index=_internal sourcetype=splunkd component=Metrics group=searchscheduler host=splunksearchhead* | timechart span=1h sum(completed), sum(skipped) by host
and then see if the searches are getting distributed properly across search heads.
This is a way better search. Thanks!
See this question (and answer)
https://answers.splunk.com/answers/337598/search-head-cluster-pre-63-we-could-run-more-numbe-2.html