However, certain switch or port failures might affect an entire SAN, thus impacting all four paths. And from the AIX chdev man page: For instance, the —S flag provides some interesting statistics and counters for hdisk devices. X We use cookies to optimize your visit to our website. As a result, the default values for the attributes are appropriate for most situations. Care should be taken when using these settings as the reserves are disabled. Indicates the number of times the service queue becomes full that is, the disk is not accepting any more service requests per second.

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When using host storage domains, the queued commands are shared. HBA microcode levels should be check periodically.

A path that is failed due to timeout policy can later be recovered by the AIX health check commands. Changes the characteristics of the device while allowing the device to remain in the Available moio. This makes AIX less dependent on the health check commands to detect path failures or to recover paths when using Fibre Channel.

If the error count is zero, then the problem is likely resolved. Pure Storage supports a maximum read and write transfer size of 4MB. Usually if a particular configuration is not supported, it is because there are known issues.

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AIX Configuration Best Practice – Hitachi Vantara Knowledge

Other PCMs might not implement this grace period. Problems setting up multipathing. The Aixx node and the storage device each have two ports connected to each of the two SAN fabrics, using a total of four ports on AIX and four ports on the storage device. Without it, the disks are identified as something like “FC Other Disk”. Hitachi provided procedures should be followed. Another new command in AIX 5.

Switch to Hybrid Mlio. With this flag, the attribute value can be changed without closing the disk and the change takes effect immediately. Indicates the average time spent by a transfer request in the wait queue. For use on versions prior to AIX 6.

IBM AIX MPIO: Best practices and considerations

For most attributes and most levels of AIX, attributes could historically only be changed on devices that were not in use. If outstanding commands sent on healthy paths exist on that device, those commands are canceled by the LUN reset operation.

For instance, the —S flag provides some interesting statistics and counters for mpioo devices. Enterprises must occasionally restructure their infrastructure to meet new IT requirements and handle scheduled outages such as scheduled system maintenance.


After the two 8-path hdisks are configured as a single HyperSwap enabled hdisk, it will have 16 paths. View Public Profile for h foorsa. Understand your logical to physical disk layout. If no disk that is accessed through that port is open, then the count stays at zero.

Following that is a table showing the error count for the remote port that was in use when the error occurred. Businesses that need to configure more than eight paths per LUN need to carefully consider the following details:.

Configure 4 or 8 paths per disk, or up to 16 paths for rare situations. However, the timeout policy attribute cannot account for all possible error scenarios.

AIX Recommended Settings

Also, consider multi-pathing for greater availability. View Public Profile for zxmaus. The new improvements, include the following items:. Installing any of the Hitachi ODM updates requires a reboot. This output shows the current link state, and then a count of errors that occurred on the adapter.