Notice that fscsi1 has a much higher error count than the error count for the other adapter, fscsi0. There are several possible combinations of using VIOS with Pure Storage, and the configurations differ depending on which one you are using. Thus the issue must be within the SAN fabric. Please repeat this for all devices. This ensures that the AIX host does not go into extended error recovery for a scheduled maintenance activity. Sign in or register to add and subscribe to comments.
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Remove the current ODM file.
AIX Recommended Settings
Install the new ODM file Reboot the host. Looking at the system mulripath 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.
Sometimes, it might be difficult for the SAN administrator to identify the source of intermittent, recurring errors. More Articles From Chris Gibson. Aox only case for more than eight paths is for specialized storage devices that configure a cluster of controllers, or for devices using Peer-to-Peer Remote Copy PPRC.
By examining these error counts, the SAN administrator can deduce the SAN fabric components that causes intermittent errors. This also indicates a possible problem with the local FC adapter.
How to Cleanup Multipathing. Comments Sign in or register to add and subscribe to comments.
And from the AIX chdev man page: 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.
However this error detection and recovery might take some time, and that delay might impact applications. T he queue depth multilath in the ODM should be treated as a possible starting point, and may need to be adjusted based on host environment variables.
The SAN administrator could make a hardware change, run lsmpio -az to zero out the error counters, then wait a few minutes before running lsmpio -are again. In this case, I had somewhat artificially plugged two of the storage device ports into a second switch, and inserted the jammer in the link between the switches mulitpath inter-switch link ISL ].
The AIX default PCMs consist of two path control modules, one to manage disk devices and another to mange tape devices. Immediately I saw that lsmpio was providing me with a lot more information than lspath.
IBM AIX MPIO: Best practices and considerations
Another feature of the recent improvements to the AIX MPIO software is the expansion of the output of the lsmpio command to include error counts per adapter and per remote port, allowing the SAN administrator to better deduce the source of intermittent, recurring errors.
When I ran the lsmpio and lspath commands on my system, I saw the following output:. This setting causes the path to be disabled.
The attributes can be displayed or changed using the SMIT, or commands in particular, the lsattr and the chdev commands.
Comments Sign in or register to add and subscribe to comments. Those path states make it obvious that there is a failure associated with the link for that particular port, and therefore, it is easy for the user to determine the source of the problem.
IBM AIX multipath I/O (MPIO) resiliency and problem determination
Carefully consider the impacts of extra, unnecessary redundancy before using more paths. Optimal performance in a failed path scenario is to ensure that the ordered path list alternate paths between separate fabrics.
Businesses that need multipafh configure more than eight paths per LUN need to carefully consider the following aiix.