mirror of https://github.com/ceph/ceph
129 lines
4.9 KiB
ReStructuredText
129 lines
4.9 KiB
ReStructuredText
==============
|
|
Health Reports
|
|
==============
|
|
|
|
|
|
How to Get Reports
|
|
==================
|
|
|
|
In general, there are two channels to retrieve the health reports:
|
|
|
|
ceph (CLI)
|
|
which sends ``health`` mon command for retrieving the health status of the cluster
|
|
mgr module
|
|
which calls ``mgr.get('health')`` for the same report in the form of a JSON encoded string
|
|
|
|
The following diagrams outline the involved parties and how the interact when the clients
|
|
query for the reports:
|
|
|
|
.. seqdiag::
|
|
|
|
seqdiag {
|
|
default_note_color = lightblue;
|
|
osd; mon; ceph-cli;
|
|
osd => mon [ label = "update osdmap service" ];
|
|
osd => mon [ label = "update osdmap service" ];
|
|
ceph-cli -> mon [ label = "send 'health' command" ];
|
|
mon -> mon [ leftnote = "gather checks from services" ];
|
|
ceph-cli <-- mon [ label = "checks and mutes" ];
|
|
}
|
|
|
|
.. seqdiag::
|
|
|
|
seqdiag {
|
|
default_note_color = lightblue;
|
|
osd; mon; mgr; mgr-module;
|
|
mgr -> mon [ label = "subscribe for 'mgrdigest'" ];
|
|
osd => mon [ label = "update osdmap service" ];
|
|
osd => mon [ label = "update osdmap service" ];
|
|
mon -> mgr [ label = "send MMgrDigest" ];
|
|
mgr -> mgr [ note = "update cluster state" ];
|
|
mon <-- mgr;
|
|
mgr-module -> mgr [ label = "mgr.get('health')" ];
|
|
mgr-module <-- mgr [ label = "heath reports in json" ];
|
|
}
|
|
|
|
Where are the Reports Generated
|
|
===============================
|
|
|
|
Aggregator of Aggregators
|
|
-------------------------
|
|
|
|
Health reports are aggregated from multiple Paxos services:
|
|
|
|
- AuthMonitor
|
|
- HealthMonitor
|
|
- MDSMonitor
|
|
- MgrMonitor
|
|
- MgrStatMonitor
|
|
- MonmapMonitor
|
|
- OSDMonitor
|
|
|
|
When persisting the pending changes in their own domain, each of them identifies the
|
|
health related issues and store them into the monstore with the prefix of ``health``
|
|
using the same transaction. For instance, ``OSDMonitor`` checks a pending new osdmap
|
|
for possible issues, like down OSDs and missing scrub flag in a pool, and then stores
|
|
the encoded form of the health reports along with the new osdmap. These reports are
|
|
later loaded and decoded, so they can be collected on demand. When it comes to
|
|
``MDSMonitor``, it persists the health metrics in the beacon sent by the MDS daemons,
|
|
and prepares health reports when storing the pending changes.
|
|
|
|
.. seqdiag::
|
|
|
|
seqdiag {
|
|
default_note_color = lightblue;
|
|
mds; mon-mds; mon-health; ceph-cli;
|
|
mds -> mon-mds [ label = "send beacon" ];
|
|
mon-mds -> mon-mds [ note = "store health metrics in beacon" ];
|
|
mds <-- mon-mds;
|
|
mon-mds -> mon-mds [ note = "encode_health(checks)" ];
|
|
ceph-cli -> mon-health [ label = "send 'health' command" ];
|
|
mon-health => mon-mds [ label = "gather health checks" ];
|
|
ceph-cli <-- mon-health [ label = "checks and mutes" ];
|
|
}
|
|
|
|
So, if we want to add a new warning related to cephfs, probably the best place to
|
|
start is ``MDSMonitor::encode_pending()``, where health reports are collected from
|
|
the latest ``FSMap`` and the health metrics reported by MDS daemons.
|
|
|
|
But it's noteworthy that ``MgrStatMonitor`` does *not* prepare the reports by itself,
|
|
it just stores whatever the health reports received from mgr!
|
|
|
|
ceph-mgr -- A Delegate Aggegator
|
|
--------------------------------
|
|
|
|
In Ceph, mgr is created to share the burden of monitor, which is used to establish
|
|
the consensus of information which is critical to keep the cluster function.
|
|
Apparently, osdmap, mdsmap and monmap fall into this category. But what about the
|
|
aggregated statistics of the cluster? They are crucial for the administrator to
|
|
understand the status of the cluster, but they might not be that important to keep
|
|
the cluster running. To address this scability issue, we offloaded the work of
|
|
collecting and aggregating the metrics to mgr.
|
|
|
|
Now, mgr is responsible for receiving and processing the ``MPGStats`` messages from
|
|
OSDs. And we also developed a protocol allowing a daemon to periodically report its
|
|
metrics and status to mgr using ``MMgrReport``. On the mgr side, it periodically sends
|
|
an aggregated report to the ``MgrStatMonitor`` service on mon. As explained earlier,
|
|
this service just persists the health reports in the aggregated report to the monstore.
|
|
|
|
.. seqdiag::
|
|
|
|
seqdiag {
|
|
default_note_color = lightblue;
|
|
service; mgr; mon-mgr-stat; mon-health;
|
|
service -> mgr [ label = "send(open)" ];
|
|
mgr -> mgr [ note = "register the new service" ];
|
|
service <-- mgr;
|
|
mgr => service [ label = "send(configure)" ];
|
|
service -> mgr [ label = "send(report)" ];
|
|
mgr -> mgr [ note = "update/aggregate service metrics" ];
|
|
service <-- mgr;
|
|
service => mgr [ label = "send(report)" ];
|
|
mgr -> mon-mgr-stat [ label = "send(mgr-report)" ];
|
|
mon-mgr-stat -> mon-mgr-stat [ note = "store health checks in the report" ];
|
|
mgr <-- mon-mgr-stat;
|
|
mon-health => mon-mgr-stat [ label = "gather health checks" ];
|
|
service => mgr [ label = "send(report)" ];
|
|
service => mgr [ label = "send(close)" ];
|
|
}
|