PendingReleaseNotes: add note about fallocate mode 0

fallocate now returns EOPNOTSUPP for mode 0

Signed-off-by: Milind Changire <mchangir@redhat.com>
(cherry picked from commit ac34dd33099925172a7d95b267b11e6693cc5648)

diff --git a/PendingReleaseNotes b/PendingReleaseNotes
index 1b597500de41651f17b5d0f5a0e9f56b3de522e8..e326b369893982e937873a8b7e9f054704c8aec5 100644 (file)
--- a/PendingReleaseNotes
+++ b/PendingReleaseNotes
@@ -1,3 +1,53 @@
+>=20.0.0
+
+* RBD: All Python APIs that produce timestamps now return "aware" `datetime`
+  objects instead of "naive" ones (i.e. those including time zone information
+  instead of those not including it).  All timestamps remain to be in UTC but
+  including `timezone.utc` makes it explicit and avoids the potential of the
+  returned timestamp getting misinterpreted -- in Python 3, many `datetime`
+  methods treat "naive" `datetime` objects as local times.
+* RBD: `rbd group info` and `rbd group snap info` commands are introduced to
+  show information about a group and a group snapshot respectively.
+* RBD: `rbd group snap ls` output now includes the group snap IDs. The header
+  of the column showing the state of a group snapshot in the unformatted CLI
+  output is changed from 'STATUS' to 'STATE'. The state of a group snapshot
+  that was shown as 'ok' is now shown as 'complete', which is more descriptive.
+* Based on tests performed at scale on a HDD based Ceph cluster, it was found
+  that scheduling with mClock was not optimal with multiple OSD shards. For
+  example, in the test cluster with multiple OSD node failures, the client
+  throughput was found to be inconsistent across test runs coupled with multiple
+  reported slow requests. However, the same test with a single OSD shard and
+  with multiple worker threads yielded significantly better results in terms of
+  consistency of client and recovery throughput across multiple test runs.
+  Therefore, as an interim measure until the issue with multiple OSD shards
+  (or multiple mClock queues per OSD) is investigated and fixed, the following
+  change to the default HDD OSD shard configuration is made:
+   - osd_op_num_shards_hdd = 1 (was 5)
+   - osd_op_num_threads_per_shard_hdd = 5 (was 1)
+  For more details see https://tracker.ceph.com/issues/66289.
+* MGR: MGR's always-on modulues/plugins can now be force-disabled. This can be
+  necessary in cases where MGR(s) needs to be prevented from being flooded by
+  the module commands when coresponding Ceph service is down/degraded.
+
+* CephFS: Modifying the FS setting variable "max_mds" when a cluster is
+  unhealthy now requires users to pass the confirmation flag
+  (--yes-i-really-mean-it). This has been added as a precaution to tell the
+  users that modifying "max_mds" may not help with troubleshooting or recovery
+  effort. Instead, it might further destabilize the cluster.
+
+* mgr/restful, mgr/zabbix: both modules, already deprecated since 2020, have been
+  finally removed. They have not been actively maintenance in the last years,
+  and started suffering from vulnerabilities in their dependency chain (e.g.:
+  CVE-2023-46136).  As alternatives, for the `restful` module, the `dashboard` module
+  provides a richer and better maintained RESTful API. Regarding the `zabbix` module,
+  there are alternative monitoring solutions, like `prometheus`, which is the most
+  widely adopted among the Ceph user community.
+
+* CephFS: EOPNOTSUPP (Operation not supported ) is now returned by the CephFS
+  fuse client for `fallocate` for the default case (i.e. mode == 0) since
+  CephFS does not support disk space reservation. The only flags supported are
+  `FALLOC_FL_KEEP_SIZE` and `FALLOC_FL_PUNCH_HOLE`.
+
 >=19.0.0
 
 * RGW: GetObject and HeadObject requests now return a x-rgw-replicated-at