AMS service uses HBase as a default storage backend. We can set the "hbase.rootdir" and "hbase.tmp.dir" have adequately sized and lightly used partitions for HBase to either local filesystem path if using Ambari Metrics in Embedded Mode mode (OR)) to the HDFS filesystem (Distributed Mode).
So this size actually depends on how much metrics data is going to be produced. Which depends on various factors like the number of components and services installed to the cluster OR the number of hosts present in the cluster OR the additional metrics that we added in the whitelist file of the ambari metrics collector.
Regarding "autocorrect" statement ... I do not think the AMS has a capability to autocorrect the Disk usage/limit.