Reducing or removing paths for a multipath LUN

Troubleshooting

Problem

This document contains information on how to deconfigure or reduce the number of multipath paths in IBM i.

Resolving The Problem

This document contains information on how to clean up old non-reporting disk paths.

To reduce the number of paths configured to external storage, do the following:

Change the configuration on the DSxxxx/FlashSystems/ESS/Shark/etc to remove the extra port(s).

Physically remove the redundant fiber cable(s), or logically/virtually remove mappings.

IPL the server so the failed (removed) paths will change from failed status to non-reporting status during DASD discovery.

Remove non-reporting disk resources
    a. Start System Service Tools (SST) using the STRSST command.
    b. Log on to System Service Tools using the appropriate SST user ID and password.
    c. Select Option 1. Start a service tool
    d. Select Option 7. Hardware service manager
    e. Select Option 4. Failed and non-reporting hardware resources
    f. Select Option 4=Remove for any DMPxxx or DDxxx resources in the list (Unknown status with a ?).
    g. Press F3=Exit three times and then press Enter to exit SST.

Run the Advanced Analysis command MULTIPATHRESETTER -RESETMP -ALL to set the number of expected paths to the actual number currently reporting:

a.	On the operating system command line, run the STRSST command.
b.	Select Option 1, Start a service tool, and press the Enter key.
c.	Select Option 4, Display/Alter/Dump, and press the Enter key.
d.	Select Option 1, Display/Alter storage, and press the Enter key.
e.	Select Option 2, Licensed Internal Code (LIC) data, and press the Enter key.
f.	Select Option 14, Advanced analysis (scroll down to see this option), and press the Enter key.
g.	At the Select Advanced Analysis Command screen, scroll down, type 1 by MULTIPATHRESETTER, and press the Enter key.
h.	At the Specify Advanced Analysis Options screen, type -RESETMP -ALL and press the Enter key.
i.	Read and follow the instructions displayed on the screen to confirm that the paths should be reset.

Notes:
1. If all redundant paths are removed, the disk resource names continue to appear as DMPxxx rather than DDxxxx.
2. Resources (DMPxxx) left behind in Hardware Service Manager for any removed paths will need to be cleaned up manually.

3. MULTIPATHRESETTER will not reset counts for failed paths, only non-reporting paths

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Historical Number

406628893

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Document Information

Modified date:
08 October 2024

UID

nas8N1015103

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