Improvements

Rook v1.6.4 is a patch release limited in scope and focusing on small feature additions and bug fixes.

Ceph

Support for separate tolerations and affinities for rbd and cephfs CSI drivers (#8006, @Rakshith-R)
Update ceph version to 15.2.13 (#8004, @leseb)
External cluster upgrades fix for CRD schema (#8042, @leseb)
Build with golang 1.16 instead of 1.15 (#7945, @subhamkrai)
Retry starting CSI drivers on initial failure (#8020, @Rakshith-R)
During uninstall stop monitoring rbd mirroring before cleanup (#8031, @leseb)
Update the backend path for RGW transit engine (#8008, @thotz)
If reducing mon count only remove one extra mon per health check (#8011, @travisn)
Parse radosgw-admin json properly for internal commands (#8000, @satoru-takeuchi)
Expand OSD PVCs only if the underlying storage class allow expansion (#8001, @iamniting)
Allow the operator log level to be changed dynamically (#7976, @subhamkrai)
Pin experimental volume replication to release-v0.1 branch (#7985, @Madhu-1)
Remove '--site-name' arg when creating bootstrap peer token (#7986, @leseb)
Do not configure external metric endpoint if not present (#7974, @leseb)
Helm chart to allow multiple filesystems (#7930, @SerialVelocity)
Rehydrate the bootstrap peer token secret on monitor changes (#7935, @leseb)