[pve-devel] [PATCH docs 3/6] ceph: troubleshooting: revise and add frequently needed information

[Alexander Zeidler]

Existing information is slightly modified and retained.

Add information:
* List which logs are usually helpful for troubleshooting
* Explain how to acknowledge listed Ceph crashes and view details
* List common causes of Ceph problems and link to recommendations for a
  healthy cluster
* Briefly describe the common problem "OSDs down/crashed"

Signed-off-by: Alexander Zeidler <a.zeidler at proxmox.com>
---
 pveceph.adoc | 72 ++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 64 insertions(+), 8 deletions(-)

diff --git a/pveceph.adoc b/pveceph.adoc
index 90bb975..4e1c1e2 100644
--- a/pveceph.adoc
+++ b/pveceph.adoc
@@ -1150,22 +1150,78 @@ The following Ceph commands can be used to see if the cluster is healthy
 ('HEALTH_OK'), if there are warnings ('HEALTH_WARN'), or even errors
 ('HEALTH_ERR'). If the cluster is in an unhealthy state, the status commands
 below will also give you an overview of the current events and actions to take.
+To stop their execution, press CTRL-C.
 
 ----
-# single time output
-pve# ceph -s
-# continuously output status changes (press CTRL+C to stop)
-pve# ceph -w
+# Continuously watch the cluster status
+pve# watch ceph --status
+
+# Print the cluster status once (not being updated)
+# and continuously append lines of status events
+pve# ceph --watch
 ----
 
+[[pve_ceph_ts]]
+Troubleshooting
+~~~~~~~~~~~~~~~
+
+This section includes frequently used troubleshooting information.
+More information can be found on the official Ceph website under
+Troubleshooting
+footnote:[Ceph troubleshooting {cephdocs-url}/rados/troubleshooting/].
+
+[[pve_ceph_ts_logs]]
+.Relevant Logs on Affected Node
+
+* xref:_disk_health_monitoring[Disk Health Monitoring]
+* __System -> System Log__ (or, for example,
+  `journalctl --since "2 days ago"`)
+* IPMI and RAID controller logs
+
+Ceph service crashes can be listed and viewed in detail by running
+`ceph crash ls` and `ceph crash info <crash_id>`. Crashes marked as
+new can be acknowledged by running, for example,
+`ceph crash archive-all`.
+
 To get a more detailed view, every Ceph service has a log file under
 `/var/log/ceph/`. If more detail is required, the log level can be
 adjusted footnote:[Ceph log and debugging {cephdocs-url}/rados/troubleshooting/log-and-debug/].
 
-You can find more information about troubleshooting
-footnote:[Ceph troubleshooting {cephdocs-url}/rados/troubleshooting/]
-a Ceph cluster on the official website.
-
+[[pve_ceph_ts_causes]]
+.Common Causes of Ceph Problems
+
+* Network problems like congestion, a faulty switch, a shut down
+interface or a blocking firewall. Check whether all {pve} nodes are
+reliably reachable on the xref:_cluster_network[corosync] network and
+on the xref:pve_ceph_install_wizard[configured] Ceph public and
+cluster network.
+
+* Disk or connection parts which are:
+** defective
+** not firmly mounted
+** lacking I/O performance under higher load (e.g. when using HDDs,
+consumer hardware or xref:pve_ceph_recommendation_raid[inadvisable]
+RAID controllers)
+
+* Not fulfilling the xref:pve_ceph_recommendation[recommendations] for
+a healthy Ceph cluster.
+
+[[pve_ceph_ts_problems]]
+.Common Ceph Problems
+ ::
+
+OSDs `down`/crashed:::
+A faulty OSD will be reported as `down` and mostly (auto) `out` 10
+minutes later. Depending on the cause, it can also automatically
+become `up` and `in` again. To try a manual activation via web
+interface, go to __Any node -> Ceph -> OSD__, select the OSD and click
+on **Start**, **In** and **Reload**. When using the shell, run on the
+affected node `ceph-volume lvm activate --all`.
++
+To activate a failed OSD, it may be necessary to
+xref:ha_manager_node_maintenance[safely] reboot the respective node
+or, as a last resort, to
+xref:pve_ceph_osd_replace[recreate or replace] the OSD.
 
 ifdef::manvolnum[]
 include::pve-copyright.adoc[]
-- 
2.39.5