openstack
/
ironic
Code Issues Proposed changes

[doc] Update power sync documentation 

Add some notes on potential UDP packet loss during conductor/BMC
power sync with IPMI, the corresponding increase in retries and
how to mitigate.

Change-Id: I4bc9a8f6f7f4da7f719a65f76ae97b1244701ee9
This commit is contained in:
Arne Wiebalck 2021-08-19 10:30:07 +02:00
parent b77a76dd63
commit 28b97db915
2 changed files with 22 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
doc/source/admin/index.rst
View File

@ -26,7 +26,7 @@ the services.
Upgrade Guide <upgrade-guide>
Security <security>
Troubleshooting FAQ <troubleshooting>
Power Sync with the Compute Service <power-sync>
Power Synchronization <power-sync>
Node Multi-Tenancy <node-multitenancy>
Fast-Track Deployment <fast-track>
Booting a Ramdisk or an ISO <ramdisk-boot>

26
doc/source/admin/power-sync.rst
View File

@ -1,6 +1,6 @@
===================================
Power Sync with the Compute Service
===================================
=====================
Power Synchronization
=====================
Baremetal Power Sync
====================
@ -10,8 +10,24 @@ value of the :oslo.config:option:`conductor.force_power_state_during_sync`
option is set to ``true`` the power state in the database will be forced on
the hardware and if it is set to ``false`` the hardware state will be forced
on the database. If this periodic task is enabled, it runs at an interval
defined by the :oslo.config:option:`conductor.sync_power_state_interval` config
option for those nodes which are not in maintenance.
defined by the :oslo.config:option:`conductor.sync_power_state_interval`
config option for those nodes which are not in maintenance. The requests sent
to Baseboard Management Controllers (BMCs) are done with a parallelism
controlled by :oslo.config:option:`conductor.sync_power_state_workers`.
The motivation to send out requests to BMCs in parallel is to handle
misbehaving BMCs which may delay or even block the synchronization otherwise.
.. note::
In deployments with many nodes and IPMI as the configured BMC protocol,
the default values of a 60 seconds power sync interval and 8 worker
threads may lead to a high rate of required retries due to client-side UDP
packet loss (visible via the corresponding warnings in the conductor
logs). While Ironic automatically retries to get the power status
for the affected nodes, the failure rate may be reduced by increasing
the power sync cycle, e.g. to 300 seconds, and/or by reducing the number
of power sync workers, e.g. to 2. Pleae keep in mind, however, that
depending on the concrete setup increasing the power sync interval may
have an impact on other components relying on up-to-date power states.
Compute-Baremetal Power Sync
============================