Signed-off-by: Scoots Hamilton <scoots@redhat.com>
The `mds_cache_reservation` parameter replaces the `mds_health_cache_threshold` in all situations except when MDS nodes sends a health alert to the Monitors indicating the cache is too large. By default, `mds_health_cache_threshold` is 150% of the maximum cache size.
Be aware that the cache limit is not a hard limit. Potential bugs in the CephFS client or MDS or misbehaving applications might cause the MDS to exceed its cache size. The `mds_health_cache_threshold` configures the cluster health warning message so that operators can investigate why the MDS cannot shrink its cache.
-
-.. warning::
-
- The memory tracking used is currently imprecise by a constant factor. This
- will be addressed in http://tracker.ceph.com/issues/22599. MDS deployments
- with large `mds_cache_memory_limit` (64GB+) should underallocate RAM to
- accommodate.