I plan to setup a number of pinot servers with hdfs as deep store. Any recommended local disk space for pinot server to cache indices and data locally? 500MB? 1TB? or more?

Wow, I have not heard of people using HDFS in a long time, now that Hadoop is on the decline. Any reason why S3, GCS, or ADLS might not be cheaper to use as a deep store?

We have many Hadoop clusters on prem. It is just much cheaper than AWS cloud for the long run.

All the segments served by a server will be downloaded to local disk before serving queries. You may plan the capacity based on the data volume on each server