IBM Support

Redundant VIOS Support

Troubleshooting


Problem

This document describes the requirements for setting up and configuring redundant VIOS support for IBM i partitions using MPIO (Multi Path I/O).

Resolving The Problem

This document describes how to set up redundant VIOS support for IBM i partitions. This is not supported on Blade servers because IVM does not support mulitple VIOS servers.

The command lspath will show the current paths.

VIOS setup

1.Set the fast fail and dynamic tracking attributes on these devices:

chdev –dev fscsiX –attr fc_err_recov=fast_fail –perm
chdev –dev fscsiX –attr dyntrk=yes –perm
2.The pair of chdev commands above must be repeated for each fscsiX device. After all fscsiX attributes have been set, restart VIOS. The restart of VIOS is required for these changes to take effect.
3.To verify the settings have been changed successfully, do the following:

lsdev –dev fscsiX –attr fc_err_recov
lsdev –dev fscsiX –attr dyntrk
Important Note: The SCSI reserve policy for each LUN (or hdisk) on both VIOS LPARs must be set to no_reserve to allow disk sharing. Some storage subsystems such as XIV default to no_reserve and do not require a change, while others such as DS4000 and DS5000 default to single_path. The change must be made prior to mapping the LUNs to IBM i, and it does not require a restart of VIOS.

To show the current reserve policy settings:
lsdev –dev hdiskX –attr reserve_policy

To set the no_reserve attribute, if necessary:
chdev –dev hdiskX –attr reserve_policy=no_reserve -perm

If the 'no_reserve' is not set prior mapping the disk, the following recovery steps should be followed. Note that while in this state, the hdisk will show a size of 0 from VIOS.
  1. You need to remove the mappings of the lun/hdisk from both vios partitions, so that they are unmapped in both places.
    rmdev -pdev vhost1 (is what I used)
  2. You then need to change the reserve for the lun/hdisk from both vios partitions.
    chdev -dev hdisk3 -attr reserve_policy=no_reserve
  3. Issuing lspv -size from both VIOS partitions should now show the correct size.
  4. Map luns/hdisk to the clients.



Recovery steps if you don't set the no_reserve prior to mapping the disk. When in this state the hdisk will show a size of 0 from VIOS.

1. Remove the mappings of the lun/hdisk from both VIOS partitions so they are unmapped in both places.
rmdev -pdev vhost1
2. Change the reserve for the lun / hdisk from both VIOS partitions.
chdev -dev hdisk3 -attr reserve_policy=no_reserve

3. lspv -size from both VIOS should now show the correct size.

4. Map luns / hdisk to the clients.

Resources

http://www-03.ibm.com/systems/resources/systems_i_Virtualization_Open_Storage.pdf
http://www.redbooks.ibm.com/redbooks/pdfs/sg247590.pdf

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Historical Number

550038605

Document Information

Modified date:
19 February 2022

UID

nas8N1012518

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