DRUID:Historical nodes Does really store data on Local Disk?


I am very new to Druid, I just setup 3 Node Druid cluster

Node1 - Co-ordinator and Overlord

Node2 - Historical and Middlemanager

Node 3 - Broker.

I am using HDFS as deepstorage as below.




Historical nodes Does really store data on Local Disk ?

Or it loads all the data from Deepstorage based on metadata information onto Memory while starting Druid process ?

Also If I am using local Storage - it has to be shared ? ( NFS Share) ?

Where i can set replication parameter for Historical nodes




Historical stores a copy of the required data in the disk apart from Memory.

Storage directory should point to HDFS. For example:


Same is the case for index logging directory.

Yes – if you have multiple Historical / Middlemanager nodes (called data nodes) then the deep storage needs to be accessible from all the nodes. Each Historical has local storage and that needn’t be shared.

Replication parameter needs to be set as part of the load rules in co-ordinator console page by editing the Retention rules. Refer to attached sreenshot of co-ord console from Druid 0.14/ Imply 2.9.

Thanks & Rgds


Hi Venkat,

Thanks for the quick response on this.


druid.storage.storageDirectory=/druid/segments - This is for Deep Storage , HDFS shared across all Historical Nodes…

For individual nodes,

druid.segmentCache.locations=[{“path”:“var/druid/segment-cache”,“maxSize”:130000000000}] - This is the Place where all the Druid segments all stored right for particular node right ?



For individual nodes , you are right.

But for DS, druid.storageDirectory should be a path to hdfs uri path location and not just /druid/segments.