Red Hat SummitQuesto contenuto non è disponibile nella lingua selezionata.
Chapter 8. Troubleshooting DM Multipath
Troubleshoot multipath configuration issues by checking daemon status, "queue_if_no_path" feature problems, and the multipathd interactive console for diagnostics.
The following issues may result in a slow or non-functioning multipath configuration:
- The multipath daemon is not running
-
If you find you have trouble implementing a multipath configuration, ensure that the
multipathddaemon is running. - Issues with
queue_if_no_pathfeature - If a multipath device is configured with the "1 queue_if_no_path" option, any process issuing I/O will hang. It remains hung until one or more paths are restored.
8.1. Troubleshooting issues with queue_if_no_path feature
Resolve I/O hangs from queue_if_no_path by setting no_path_retry N in /etc/multipath.conf, limiting retries when all paths fail. You can also disable queueing at runtime for specific Logical Unit Numbers (LUNs) to prevent applications from hanging during path outages.
Procedure
Disable queueing:
For a specific device:
# multipathd disablequeueing map deviceFor all devices:
# multipathd disablequeueing mapsAfter you disable queueing, it will remain disabled until you restart or reload
multipathd.
Reset queueing to a previous value:
For a specific device:
# multipathd restorequeueing map deviceFor all devices:
# multipathd restorequeueing maps
8.2. Troubleshooting with the multipathd interactive console
Use the multipathd -k interactive console to troubleshoot multipath issues in real time. This console provides access to status info, config details, and control commands. Type help for commands and press Ctrl+D to exit without disrupting services.
Procedure
Display the multipath configuration, including the default values, before exiting the console:
# multipathd -kmultipathd> show config multipathd> Ctrl+DEnsure that multipath picked up all changes to the
multipath.conffile:# multipathd -kmultipathd> reconfigure multipathd> Ctrl+DEnsure that the path checker is working properly:
# multipathd -kmultipathd> show paths multipathd> Ctrl+DYou can also run a single
multipathdinteractive command directly from the command line, without starting the interactive console. For example, to check that multipath picks up all changes to themultipath.conffile, run the following command:# multipathd reconfigure
'%20d='M201.5%20305.5c-13.8%200-24.9-11.1-24.9-24.6%200-13.8%2011.1-24.9%2024.9-24.9%2013.6%200%2024.6%2011.1%2024.6%2024.9%200%2013.6-11.1%2024.6-24.6%2024.6zM504%20256c0%20137-111%20248-248%20248S8%20393%208%20256%20119%208%20256%208s248%20111%20248%20248zm-132.3-41.2c-9.4%200-17.7%203.9-23.8%2010-22.4-15.5-52.6-25.5-86.1-26.6l17.4-78.3%2055.4%2012.5c0%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.3%2024.9-24.9s-11.1-24.9-24.9-24.9c-9.7%200-18%205.8-22.1%2013.8l-61.2-13.6c-3-.8-6.1%201.4-6.9%204.4l-19.1%2086.4c-33.2%201.4-63.1%2011.3-85.5%2026.8-6.1-6.4-14.7-10.2-24.1-10.2-34.9%200-46.3%2046.9-14.4%2062.8-1.1%205-1.7%2010.2-1.7%2015.5%200%2052.6%2059.2%2095.2%20132%2095.2%2073.1%200%20132.3-42.6%20132.3-95.2%200-5.3-.6-10.8-1.9-15.8%2031.3-16%2019.8-62.5-14.9-62.5zM302.8%20331c-18.2%2018.2-76.1%2017.9-93.6%200-2.2-2.2-6.1-2.2-8.3%200-2.5%202.5-2.5%206.4%200%208.6%2022.8%2022.8%2087.3%2022.8%20110.2%200%202.5-2.2%202.5-6.1%200-8.6-2.2-2.2-6.1-2.2-8.3%200zm7.7-75c-13.6%200-24.6%2011.1-24.6%2024.9%200%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.1%2024.9-24.6%200-13.8-11-24.9-24.9-24.9z'/%3e%3c/svg%3e){kind=small}