ceph/PendingReleaseNotes

>=18.0.0

* The RGW policy parser now rejects unknown principals by default. If you are
  mirroring policies between RGW and AWS, you may wish to set
  "rgw policy reject invalid principals" to "false". This affects only newly set
  policies, not policies that are already in place.
* RGW's default backend for `rgw_enable_ops_log` changed from RADOS to file.
  The default value of `rgw_ops_log_rados` is now false, and `rgw_ops_log_file_path`
  defaults to "/var/log/ceph/ops-log-$cluster-$name.log".
* The SPDK backend for BlueStore is now able to connect to an NVMeoF target.
  Please note that this is not an officially supported feature.
* RGW's pubsub interface now returns boolean fields using bool. Before this change,
  `/topics/<topic-name>` returns "stored_secret" and "persistent" using a string
  of "true" or "false" with quotes around them. After this change, these fields
  are returned without quotes so they can be decoded as boolean values in JSON.
  The same applies to the `is_truncated` field returned by `/subscriptions/<sub-name>`.
* RGW's response of `Action=GetTopicAttributes&TopicArn=<topic-arn>` REST API now
  returns `HasStoredSecret` and `Persistent` as boolean in the JSON string
  encoded in `Attributes/EndPoint`.
* All boolean fields previously rendered as string by `rgw-admin` command when
  the JSON format is used are now rendered as boolean. If your scripts/tools
  relies on this behavior, please update them accordingly. The impacted field names
  are:
  * absolute
  * add
  * admin
  * appendable
  * bucket_key_enabled
  * delete_marker
  * exists
  * has_bucket_info
  * high_precision_time
  * index
  * is_master
  * is_prefix
  * is_truncated
  * linked
  * log_meta
  * log_op
  * pending_removal
  * read_only
  * retain_head_object
  * rule_exist
  * start_with_full_sync
  * sync_from_all
  * syncstopped
  * system
  * truncated
  * user_stats_sync
* RGW: The beast frontend's HTTP access log line uses a new debug_rgw_access
  configurable. This has the same defaults as debug_rgw, but can now be controlled
  independently.
* RBD: The semantics of compare-and-write C++ API (`Image::compare_and_write`
  and `Image::aio_compare_and_write` methods) now match those of C API.  Both
  compare and write steps operate only on `len` bytes even if the respective
  buffers are larger. The previous behavior of comparing up to the size of
  the compare buffer was prone to subtle breakage upon straddling a stripe
  unit boundary.
* RBD: compare-and-write operation is no longer limited to 512-byte sectors.
  Assuming proper alignment, it now allows operating on stripe units (4M by
  default).
* RBD: New `rbd_aio_compare_and_writev` API method to support scatter/gather
  on both compare and write buffers.  This compliments existing `rbd_aio_readv`
  and `rbd_aio_writev` methods.
* The 'AT_NO_ATTR_SYNC' macro is deprecated, please use the standard 'AT_STATX_DONT_SYNC'
  macro. The 'AT_NO_ATTR_SYNC' macro will be removed in the future.
* Trimming of PGLog dups is now controlled by the size instead of the version.
  This fixes the PGLog inflation issue that was happening when the on-line
  (in OSD) trimming got jammed after a PG split operation. Also, a new off-line
  mechanism has been added: `ceph-objectstore-tool` got `trim-pg-log-dups` op
  that targets situations where OSD is unable to boot due to those inflated dups.
  If that is the case, in OSD logs the "You can be hit by THE DUPS BUG" warning
  will be visible.
  Relevant tracker: https://tracker.ceph.com/issues/53729
* RBD: `rbd device unmap` command gained `--namespace` option.  Support for
  namespaces was added to RBD in Nautilus 14.2.0 and it has been possible to
  map and unmap images in namespaces using the `image-spec` syntax since then
  but the corresponding option available in most other commands was missing.
* RGW: Compression is now supported for objects uploaded with Server-Side Encryption.
  When both are enabled, compression is applied before encryption. Earlier releases
  of multisite do not replicate such objects correctly, so all zones must upgrade to
  Reef before enabling the `compress-encrypted` zonegroup feature: see
  https://docs.ceph.com/en/reef/radosgw/multisite/#zone-features and note the
  security considerations.
* RGW: the "pubsub" functionality for storing bucket notifications inside Ceph
  is removed. Together with it, the "pubsub" zone should not be used anymore.
  The REST operations, as well as radosgw-admin commands for manipulating
  subscriptions, as well as fetching and acking the notifications are removed 
  as well.
  In case that the endpoint to which the notifications are sent maybe down or 
  disconnected, it is recommended to use persistent notifications to guarantee 
  the delivery of the notifications. In case the system that consumes the 
  notifications needs to pull them (instead of the notifications be pushed 
  to it), an external message bus (e.g. rabbitmq, Kafka) should be used for 
  that purpose.
* RGW: The serialized format of notification and topics has changed, so that 
  new/updated topics will be unreadable by old RGWs. We recommend completing 
  the RGW upgrades before creating or modifying any notification topics.
* RBD: Trailing newline in passphrase files (`<passphrase-file>` argument in
  `rbd encryption format` command and `--encryption-passphrase-file` option
  in other commands) is no longer stripped.
* RBD: Support for layered client-side encryption is added.  Cloned images
  can now be encrypted each with its own encryption format and passphrase,
  potentially different from that of the parent image.  The efficient
  copy-on-write semantics intrinsic to unformatted (regular) cloned images
  are retained.
* CEPHFS: Rename the `mds_max_retries_on_remount_failure` option to
  `client_max_retries_on_remount_failure` and move it from mds.yaml.in to
  mds-client.yaml.in because this option was only used by MDS client from its
  birth.
* The `perf dump` and `perf schema` commands are deprecated in favor of new
  `counter dump` and `counter schema` commands. These new commands add support
  for labeled perf counters and also emit existing unlabeled perf counters. Some
  unlabeled perf counters became labeled in this release, with more to follow in
  future releases; such converted perf counters are no longer emitted by the
  `perf dump` and `perf schema` commands.
* `ceph mgr dump` command now outputs `last_failure_osd_epoch` and
  `active_clients` fields at the top level.  Previously, these fields were
  output under `always_on_modules` field.
* `ceph mgr dump` command now displays the name of the mgr module that
  registered a RADOS client in the `name` field added to elements of the
  `active_clients` array. Previously, only the address of a module's RADOS
  client was shown in the `active_clients` array.
* RBD: All rbd-mirror daemon perf counters became labeled and as such are now
  emitted only by the new `counter dump` and `counter schema` commands.  As part
  of the conversion, many also got renamed to better disambiguate journal-based
  and snapshot-based mirroring.
* RBD: list-watchers C++ API (`Image::list_watchers`) now clears the passed
  `std::list` before potentially appending to it, aligning with the semantics
  of the corresponding C API (`rbd_watchers_list`).
* The rados python binding is now able to process (opt-in) omap keys as bytes
  objects. This enables interacting with RADOS omap keys that are not decodeable as
  UTF-8 strings.
* Telemetry: Users who are opted-in to telemetry can also opt-in to
  participating in a leaderboard in the telemetry public
  dashboards (https://telemetry-public.ceph.com/). Users can now also add a
  description of the cluster to publicly appear in the leaderboard.
  For more details, see:
  https://docs.ceph.com/en/latest/mgr/telemetry/#leaderboard
  See a sample report with `ceph telemetry preview`.
  Opt-in to telemetry with `ceph telemetry on`.
  Opt-in to the leaderboard with
  `ceph config set mgr mgr/telemetry/leaderboard true`.
  Add leaderboard description with:
  `ceph config set mgr mgr/telemetry/leaderboard_description ‘Cluster description’`.
* CEPHFS: After recovering a Ceph File System post following the disaster recovery
  procedure, the recovered files under `lost+found` directory can now be deleted.
* core: cache-tiering is now deprecated.
* mClock Scheduler: The mClock scheduler (default scheduler in Quincy) has
  undergone significant usability and design improvements to address the slow
  backfill issue. Some important changes are:
  * The 'balanced' profile is set as the default mClock profile because it
    represents a compromise between prioritizing client IO or recovery IO. Users
    can then choose either the 'high_client_ops' profile to prioritize client IO
    or the 'high_recovery_ops' profile to prioritize recovery IO.
  * QoS parameters like reservation and limit are now specified in terms of a
    fraction (range: 0.0 to 1.0) of the OSD's IOPS capacity.
  * The cost parameters (osd_mclock_cost_per_io_usec_* and
    osd_mclock_cost_per_byte_usec_*) have been removed. The cost of an operation
    is now determined using the random IOPS and maximum sequential bandwidth
    capability of the OSD's underlying device.
  * Degraded object recovery is given higher priority when compared to misplaced
    object recovery because degraded objects present a data safety issue not
    present with objects that are merely misplaced. Therefore, backfilling
    operations with the 'balanced' and 'high_client_ops' mClock profiles may
    progress slower than what was seen with the 'WeightedPriorityQueue' (WPQ)
    scheduler.
  * The QoS allocations in all the mClock profiles are optimized based on the above
    fixes and enhancements.
  * For more detailed information see:
    https://docs.ceph.com/en/latest/rados/configuration/mclock-config-ref/
* mgr/snap_schedule: The snap-schedule mgr module now retains one less snapshot
  than the number mentioned against the config tunable `mds_max_snaps_per_dir`
  so that a new snapshot can be created and retained during the next schedule
  run.

>=17.2.1

* The "BlueStore zero block detection" feature (first introduced to Quincy in
https://github.com/ceph/ceph/pull/43337) has been turned off by default with a
new global configuration called `bluestore_zero_block_detection`. This feature,
intended for large-scale synthetic testing, does not interact well with some RBD
and CephFS features. Any side effects experienced in previous Quincy versions
would no longer occur, provided that the configuration remains set to false.
Relevant tracker: https://tracker.ceph.com/issues/55521

* telemetry: Added new Rook metrics to the 'basic' channel to report Rook's
  version, Kubernetes version, node metrics, etc.
  See a sample report with `ceph telemetry preview`.
  Opt-in with `ceph telemetry on`.

  For more details, see:

  https://docs.ceph.com/en/latest/mgr/telemetry/

* OSD: The issue of high CPU utilization during recovery/backfill operations
  has been fixed. For more details, see: https://tracker.ceph.com/issues/56530.

>=15.2.17

* OSD: Octopus modified the SnapMapper key format from
  <LEGACY_MAPPING_PREFIX><snapid>_<shardid>_<hobject_t::to_str()>
  to
  <MAPPING_PREFIX><pool>_<snapid>_<shardid>_<hobject_t::to_str()>
  When this change was introduced, 94ebe0e also introduced a conversion
  with a crucial bug which essentially destroyed legacy keys by mapping them
  to
  <MAPPING_PREFIX><poolid>_<snapid>_
  without the object-unique suffix. The conversion is fixed in this release.
  Relevant tracker: https://tracker.ceph.com/issues/56147
  
* Cephadm may now be configured to carry out CephFS MDS upgrades without
reducing ``max_mds`` to 1. Previously, Cephadm would reduce ``max_mds`` to 1 to
avoid having two active MDS modifying on-disk structures with new versions,
communicating cross-version-incompatible messages, or other potential
incompatibilities. This could be disruptive for large-scale CephFS deployments
because the cluster cannot easily reduce active MDS daemons to 1.
NOTE: Staggered upgrade of the mons/mgrs may be necessary to take advantage
of the feature, refer this link on how to perform it:
https://docs.ceph.com/en/quincy/cephadm/upgrade/#staggered-upgrade
Relevant tracker: https://tracker.ceph.com/issues/55715

* Introduced a new file system flag `refuse_client_session` that can be set using the
`fs set` command. This flag allows blocking any incoming session
request from client(s). This can be useful during some recovery situations
where it's desirable to bring MDS up but have no client workload.
Relevant tracker: https://tracker.ceph.com/issues/57090

* New MDSMap field `max_xattr_size` which can be set using the `fs set` command.
  This MDSMap field allows to configure the maximum size allowed for the full
  key/value set for a filesystem extended attributes.  It effectively replaces
  the old per-MDS `max_xattr_pairs_size` setting, which is now dropped.
  Relevant tracker: https://tracker.ceph.com/issues/55725