This is the fourth minor release in the Squid series.
We recommend that all users update to this release.

Notable Changes
---------------
OSD / BlueStore
---------------

* BlueFS: Increased the default WAL volume size to 1GB to prevent ENOSPC failures.
* Volume Selection: Fixed the usage of bluestore_volume_selection_reserved_factor and updated row naming conventions in RocksDBBlueFSVolumeSelector.
* Health: Added a time_added field to mon_info_t to prevent freshly added monitors from incorrectly triggering a MON_DOWN health status.
* Tooling: Updated monmaptool to correctly respect set features when adding addresses.

RADOS / Manager (mgr)
---------------------

* RADOS pybind: Fixed a parameter reversal bug in WriteOp.zero() where offset and length were swapped when calling the underlying C API.
* Daemon Health: Modified the manager to clear health metrics for down or out OSDs instead of removing them entirely from the daemon state.
* Autoscaler: Updated pg_autoscale_mode logic to accurately reflect the no_autoscale flag in both standard and JSON command outputs.

RADOS Gateway (RGW)
-------------------

* Notifications: Resolved a reserved_size drift in the 2pc_queue causing ENOSPC errors and fixed a leak where overhead was not properly decremented during commit/abort.
* Multipart Uploads: Fixed an issue where tags could not be retrieved from objects created via multipart uploads.
* Kafka Integration: Updated the internal Kafka version support to 3.9.2.

CephFS / MDS
------------

* Fragments: Simplified fragment printing and corrected frag_t endianness conversion for network and storage consistency.
* FUSE Client: Updated the FUSE client to clarify that fallocate disk space reservation is only supported with specific flags like FALLOC_FL_KEEP_SIZE.
* Metadata: Updated the MDS to dump frag_t as an object and included sysinfo in the status command output for better diagnostics.

Dashboard
---------

* Services: Fixed a bug where changing MDS placement to a label incorrectly triggered the creation of an entirely new MDS service.
* Access Control: Fixed role-based access control permissions and added missing types to the mgr-module list.

librbd & rbd-mirror
-------------------

* RBD: Introduced a new ``RBD_LOCK_MODE_EXCLUSIVE_TRANSIENT`` policy for ``rbd_lock_acquire()``. This is a low-level interface intended to allow a peer to grab exclusive lock manually for short periods of time with other peers pausing their activity and waiting for the lock to be released rather than instantly aborting I/O and returning an error. It's possible to switch from ``RBD_LOCK_MODE_EXCLUSIVE`` to ``RBD_LOCK_MODE_EXCLUSIVE_TRANSIENT`` policy and vice versa even if the lock is already held.

We recommend users to update to this release.
For detailed release notes with links & changelog please refer to the
official blog entry at https://ceph.io/en/news/blog/2026/v19-2-4-squid-released/

Getting Ceph
------------
* Git at git://github.com/ceph/ceph.git
* Tarball at https://download.ceph.com/tarballs/ceph-19.2.4.tar.gz
* Containers at https://quay.io/repository/ceph/ceph
* For packages, see https://docs.ceph.com/en/latest/install/get-packages/
* Release git sha1: 7cc0193a616a3333d22b7762037fa5b73a4d06a6