Once the server disk usage passes a certain threshold, Solr will roll over the oldest loaded core.
With AlwaysDeleteColdPartitions=False, older cores are unmounted, but will not be removed automatically. So the server never goes below the disk threshold
Resolution
Disk usage needs to be reduced below the MaxEventStoreSizeInPercent (default 90%)
Remove old cores to a separate storage location
Increase drive space on server
Additional Information
It is not recommended that cold cores be stored on the /var/cb partition
New cores can be remounted manually, but the cb.user_mounted file will need to be removed: https://community.carbonblack.com/t5/Knowledge-Base/EDR-How-to-remount-Cold-Partitions/ta-p/62446
To view mounted cores, run:
curl "http://127.0.0.1:8080/solr/admin/cores?action=STATUS&wt=json&indexInfo=false&indent=true" | grep name