A disabled path is only recovered by manual user intervention using the chpath command to re-enable the path. In this mode, the PCM only sends path health checks down paths that are marked as failed. Monitor using the fcstat command. System reliability and availability are increased by a careful consideration of the user-modifiable options in each system configuration. Sign in or register to add and subscribe to comments. The AIX and device ports can be connected to the same FC switch or to two different switches in the same fabric.

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Looking at the system error report, there may be TEMP disk errors, indicating that certain Small Computer System Interface SCSI commands failed on their first attempt, but were successful when retried, perhaps down a different path. Find all posts by zxmaus. You can run the current command to check which version of the Pure ODM file you are currently running: This setting causes AIX to fail the path after a single command timeout, assuming that the device has at least one other path that is not in the failed state.

The disk attributes described in the following sections can be displayed by using the lsattr command, and can be changed with the chdev command. If a component has a solid, permanent failure, the failure can be easily detected either by the MPIO software in AIX or by the firmware in the storage device. The path priority values are ignored by this algorithm.

AIX Configuration Best Practice

Thus if a single adapter fails, the other adapter provides access to the storage device. System reliability and availability are increased by a careful consideration of the user-modifiable options in each system configuration. For such a device, the PCM uses just the paths to the active or preferred controller as long as there is at least one such path that is enabled and not failed.

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The -a flag mpii adapter shows the local adapters; the -r flag for remote ports shows the target device ports that each adapter is connected to and the number of paths in mpi possible state, as shown in Example 1. However this error detection and recovery might take some time, and that delay might impact applications.

View Public Profile for csorhand. When using “Additional setteing” in Edit Host Group window: Subscribe and stay informed about: The health checker never probes paths that are in a Disabled or Missing state. A path stays in the Degraded state from the time it experiences certain errors until there have been five successful health check commands processed on that path.

The lspath command or in newer technology levels, the lsmpio command can be used to determine the MPIO paths that are associated with specific SAN ports. In this mode, the PCM only sends path health checks down paths that are marked as failed. This represents the legacy behavior, where a command may be mpik on the same path that just experienced a command timeout.

For example, perhaps the optical source on an FC port is becoming weak, a connection between the fiber and the port of an FC switch is not secure, or some device on a SAN fabric is malfunctioning in a way that is flooding that SAN fabric with extraneous traffic. Carefully mpiio the impacts of extra, unnecessary redundancy before using more paths.

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T he queue depth setting in the ODM should be treated as a possible starting point, and may need to be adjusted based on host environment variables.

Remove the current ODM file. Your browser does not support iframes.

IBM Systems Magazine – New lsmpio Command Provides Better View of MPIO | AIX | IBM Systems Magazine

Best practice is to make the queue depth the same in both the server and client partition. When the SAN administrator specifies the -e flag, the lsmpio command output includes error counts for the local adapters and for the remote ports. This example uses the —a option to monitor the adapter as well iostat —aD —d hdisk9 10 Adapter: Another feature mentioned in the IBM article was the new —U flag for the chdev command.

The enhancements in the new TL attempt to distinguish these induced errors from errors caused by the SAN issue to better identify the good paths and the problematic paths.

Sign in or register to add and subscribe to comments. This is just an example. It is not a driver. The axi command implements the -a and -r flags to show the local and remote FC ports used by the disks. I highly recommend you take the time to read this article in full. Some third-party ODMs use a different default value. The following sections discuss the output of various samples of the lsmpio command.