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The AIX 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. Note that there could be cases where the error total listed directly under the adapter exceed the sum of the errors on the remote ports under the adapter, as some errors may not be associated with a particular remote port. Another feature mentioned in the IBM article was the new —U flag for the chdev command. More Articles From Chris Gibson. There are four paths between AIX and the storage device for each of the two distinct SAN fabrics, for a total of eight paths. For most attributes and most levels of AIX, attributes could historically only be changed on devices that were not in use.

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Thus the issue must be within the SAN fabric. When disabling multiple paths for multiple LUNs, rmpath is simpler than chpathas it does not have to be run on a per-disk basis. Hi, I know the concept of multipathing, but would like to know how to configure multipathing in AIX.

IBM AIX multipath I/O (MPIO) resiliency and problem determination

View Public Profile for manoj. For the newest technology levels of AIX at the time of publishing this articlesome disk attributes on some devices support the -U flag on the chdev command. The -a flag for 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 each possible state, as shown in Example 1.


In order to upgrade to the latest version of the ODM you will need to first remove the old one.

Read The Current Issue: This will require a reboot on the initiator, and the steps are as follows: Also notice that the errors occurred across all of the remote ports accessed by fscsi1.

When the lsmpio command is used, you might see output as shown in Example 3.

Versions prior to AIX 6. SAN administrators may use several configuration techniques to maximize redundancy.

Optimal performance in a failed path scenario is to aiix that the ordered path list alternate paths between separate fabrics. The miltipath sections discuss the output of various samples of the lsmpio command. What you set it to will need to be unique, you can set multiath value to “0x1” for example.

Multpiath lsmpio command in older technology levels of AIX supports these two flags. Note that there could be cases where the error total listed directly under the adapter exceed the sum of the errors on the remote ports under the adapter, as some errors may not be associated with a particular remote port.

Pure Storage supports a maximum read and write transfer size of 4MB. Thus if a single adapter fails, the other adapter provides access to the storage device. If you would like to change your cookie settings at any time please view our privacy policy for additional information.

Also, note that two different storage device ports have errors indicating that the issue is not associated with a single port on the storage device. Likewise, for such failures it is also easy for the AIX MPIO software to detect and react to the failure ai discontinuing the use of any path that uses the failed component. Each MPIO-capable device driver adds the paths to a device from its immediate parent or parents.


Multiple Path I/O

View Public Profile for kah00na. 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. So how might the SAN administrator use the error count?

The AIX system error report shows errors for a particular FC port and shows disk path failures for paths using that particular port. If you are running this version, run the following to clear the reservation from AIX before proceeding: 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.

Keep in mind that you will need to manually make this change anytime you overwrite the ODM i. Other PCMs might not implement this grace period. Similar to the first case, this indicates an issue with one particular FC port, but this time the problematic port is on the storage device.

ACA is supported starting in Purity 3. So, it may continue to attempt to use the path that contains the failing component. The fileset allows your AIX multipafh to correctly identify the disks as Hitachi disks. Find all posts by kah00na.