The disk usage metric shows the percentage of space used on the data partition of a node. This includes the main Cassandra files containing your data as well as working files such as snapshots for backups and temporary copies of files used for compactions.
We recommend that disk usage is kept to less than 70% during normal running to allow temporary working space for Cassandra operations. If your cluster is regularly exceeding 70% then you should consider adding capacity or removing data.
Instaclustr Support monitors disk use for all managed clusters and will notify you if your cluster is exceeding recommended levels of disk usage.