Here is some SPL to get useful information via REST on indexes within your Splunk environment:
| REST /services/data/indexes | eval currentDBSizeMB=tostring(currentDBSizeMB, "commas") | eval totalEventCount=tostring(totalEventCount, "commas") | eval frozenTimePeriodInHours=(frozenTimePeriodInSecs/60/60) | table title splunk_server currentDBSizeMB frozenTimePeriodInHours maxTime minTime totalEventCount