Query super slow whenever first time on an index

Similar query

first time: 19.301 s

second time: 0.314 s

index status after the first query

cluster status

You have 973.385.595 docs with 1.123.353.812.871 (1.1 Tb if I'm not mistaken) with only 2 data nodes?

That might explain that it takes a lot of time to read the data from disk the first time. On the second run, I guess that the FS Cache is playing its role.

What is the query you are running BTW?

Ho! I just saw that BTW:

"spins": "true"

Use SSD Drives!










            "query":"event_code:5156 AND _type:logs AND exa_parser_name:q-5156 AND host:QRADAR_5156_HOST_NAME AND data_type:process-network AND dest_port:88"







Yes 1T data.

It works well on similar physical machines.

If you did not notice I updated my answer in the meantime.


  1. is there anyway to get the time spend on fetching from disk?
  2. I tried close the index and reopen the index, seems query is still fast. FS cache not clear after close the index?
  1. I don't know
  2. Why would it? The OS does not know that we are not going to access the files anymore.

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