Description of problem:

The active MGR log message "Detected new or changed devices” is filling up every 30 mins even if there is no activity or change observed in the cluster. The requirement is to log above messages only if there is an actual change on the node.

We have tried to look up in the code snippet that is generating the log message as below.
~~~
The code is here: mgr/cephadm/inventory.py:
    def devices_changed(self, host: str, b: List[inventory.Device]) -> bool:
        a = self.devices[host]
        if len(a) != len(b):
            return True
        aj = {d.path: d.to_json() for d in a}
        bj = {d.path: d.to_json() for d in b}
        if aj != bj:
            self.mgr.log.info("Detected new or changed devices on %s" % host)
            return True
        return False
~~~

And while dumping the values of both aj & bj variables, observed that the difference is only for the field "created" which is 30 mins.
     - This 30 mins is after which the above function is called coming from the configuration parameter mgr/cephadm/device_cache_timeout

~~~
aj: {'/dev/sdX': {'ceph_device': None, 'rejected_reasons': [], 'available': True, 'path': '/dev/sdX', 'sys_api': {'human_readable_size': '10.00 GB', 'locked': 0, 'model': 'QEMU HARDDISK', 'nr_requests': '256', 'partitions': {}, 'path': '/dev/sdX', 'removable': '0', 'rev': '2.5+', 'ro': '0', 'rotational': '1', 'sas_address': '', 'sas_device_handle': '', 'scheduler_mode': 'mq-deadline', 'sectors': 0, 'sectorsize': '512', 'size': 10737418240.0, 'support_discard': '4096', 'vendor': 'QEMU'}, 'created': '2022-10-20T01:07:32.604710Z', 'lvs': [], 'human_readable_type': 'hdd', 'device_id': 'QEMU_QEMU_HARDDISK_15bbXXXX-XXXX-40e8-XXXX-946a21dXXXXXX', 'lsm_data': {}}} 
-------------------------------------------------
 bj: {'/dev/sdX': {'ceph_device': None, 'rejected_reasons': [], 'available': True, 'path': '/dev/sdX', 'sys_api': {'human_readable_size': '10.00 GB', 'locked': 0, 'model': 'QEMU HARDDISK', 'nr_requests': '256', 'partitions': {}, 'path': '/dev/sdX', 'removable': '0', 'rev': '2.5+', 'ro': '0', 'rotational': '1', 'sas_address': '', 'sas_device_handle': '', 'scheduler_mode': 'mq-deadline', 'sectors': 0, 'sectorsize': '512', 'size': 10737418240.0, 'support_discard': '4096', 'vendor': 'QEMU'}, 'created': '2022-10-20T01:38:30.355023Z', 'lvs': [], 'human_readable_type': 'hdd', 'device_id': 'QEMU_QEMU_HARDDISK_15bbXXXX-XXXX-40e8-XXXX-946a21dXXXXX', 'lsm_data': {}}}
~~~

Additionally, we tried to look further in the code, and observed that the value for the field "created" gets updated or applied only once at the below location in code.
- https://github.com/ceph/ceph/blob/main/src/python-common/ceph/deployment/inventory.py#L74-L77

Version-Release number of selected component (if applicable): RHCS 5.2


How reproducible: Always


Steps to Reproduce:
1. Simply deploy or upgrade an RHCS 5 envrionment
2. Monitor the active mgr logs for the message "Detected new or changed devices"

Actual results: "Detected new or changed devices" log message is filling up even if there is no actual change.


Expected results: Log the above message only if there is an actual change on the node.