IBM Support

Migrate to AIXPCM using "Manage_Disk_Drivers" Command

How To


Summary

Using the manage_disk_drivers command allows users to switch Path Control Modules on an AIX system without direct or extended application impact. However, a reboot of the host is required to make the change effective.
When migrating to AIXPCM in a PowerHA configuration, this procedure can be performed on one side of the cluster first, reboot, then proceed with the other side of the cluster

Objective

The objective is to allow customers to migrate away from SDDPCM multi-pathing and onto AIXPCM in response to the planned End of support (EOS) for SDDPCM with IBM storage products. The support for SDDPCM will officially end on June 30, 2020.

Environment

The environment includes AIX stand-alone Lpars, VIO Clients, VIOS , supporting VSCSI or NPIV adapter configurations. In addition, this procedure can be used in host cluster environments, such as PowerHA, Oracle, DB2 and Spectrum Scale(GPFS), single node at a time.
When migrating to AIXPCM in a PowerHA or other cluster configuration, this procedure can be performed on one side of the cluster first, reboot, then proceed with the other side of the cluster
AIX 5.3 does not support the AIXPCM multi-path driver with IBM Storage. Only AIX 6.1 TL09 SP12 and above are supported.
Power 9 hardware platforms and related OS levels were not tested with SDDPCM, only AIXPCM. Therefore, P9 does not support SDDPCM on any version of AIX.

Steps

The manage_disk_drivers command allows administrators to choose between different Path Control Modules (PCMs), or between using a PCM and configuring the disks as non-MPIO disks.

It is the easiest and less intrusive method for transitioning from SDDPCM to AIX MPIO default PCM.

Based on the type of storage controller configured, you can run the command to list out the available options.

#manage_disk_drivers -l | grep -i svc 

#manage_disk_drivers -l | grep -i 2107ds8k

The -l option shows a list of all options available (the columns show the device family, the driver currently used by that family, and the different options available).

IBMSVC         NO_OVERRIDE     NO_OVERRIDE,AIX_AAPCM,AIX_non_MPIO

2107DS8K       NO_OVERRIDE     NO_OVERRIDE,AIX_AAPCM,AIX_non_MPIO

The "NO_OVERRIDE" option indicates that the configuration is not overridden by manage_disk_drivers, and so the device family is configured based on the available ODM to match that family. The ODM supplied by SDDPCM takes precedence over the AIX default PCM ODM.  So a value of "NO_OVERRIDE" indicates that SDDPCM is used to configure devices of that family, if SDDPCM is installed.  If SDDPCM is not installed, then the AIX default PCM is used.

By selecting the "AIX_AAPCM" option, the administrator can instruct AIX to use the AIX default PCM even if SDDPCM is installed. The AIX LPAR must be rebooted in order for the disks to be reconfigured to use the AIX PCM.  Once AIX is rebooted, SDDPCM is no longer in use for the disk family specified in the manage_disk_drivers command.  If no disks are using SDDPCM, then the SDDPCM filesets may be uninstalled using SMIT or running the installp -ug command

Note: The values of the attributes of the disks are not preserved during this conversion.  In particular, the AIX default PCM uses the "single_path" reservation policy as the default, and the "fail_over" algorithm as the default algorithm.

If the disks being switched from SDDPCM to AIX PCM are shared among multiple nodes in a cluster or VIOS configuration, this default reservation policy must be changed before the disk is opened.  If this is not changed, other nodes in the cluster or VIOS configuration will lose access to the shared disks until the reservation policy is changed.

The chdev command may be used to change the reservation policy. This also applies to VSCSI backing disks in a dual VIOS environment.

If possible, it is a good idea to add the recommended values to the predefined attributes in ODM. These values should be applied BEFORE rebooting your system into AIXPCM mode.

Note: It is highly recommended that a bosboot be executed when the "chdef" command has been issued prior to a reboot to avoid losing changes to the ODM.

Examples:

# chdef -a queue_depth=32 -c disk -s fcp -t mpioosdisk
queue_depth changed

# chdef -a reserve_policy=no_reserve -c disk -s fcp -t mpioosdisk
reserve_policy changed

# chdef -a algorithm=shortest_queue -c PCM -s friend -t fcpother
algorithm changed

For DS8K:

# chdef -a queue_depth=32 -c disk -s fcp -t aixmpiods8k
queue_depth changed

# chdef -a reserve_policy=no_reserve -c disk -s fcp -t aixmpiods8k
reserve_policy changed

Please take note of the following important information:

Note1: Any future LUN will now have the recommended values. Existing disks will acquire new attribute settings once reboot is completed.

Note2: Removing SDDPCM will set the queue to the default value of 20. Any modification made to the queue depth prior to removal will need to be reapplied.

Note3: The default path selection algorithm for AIXPCM is "fail_over". The AIX PCM supports the "shortest_queue" algorithm which is similar to SDD PCM's "load_balance" algorithm. The chdev command may be used to set the algorithm, though it may also be necessary to set the reserve policy when changing the algorithm. For example, to set hdisk5 to use the "shortest_queue" algorithm, execute this command: chdev -l hdisk5 -a algorithm=shortest_queue -a reserve_policy=no_reserve

Note4: Multi-path management commands differ between AIXPCM and SDDPCM. If the SDDPCM is removed from your system any scripts that have been generated that utilize these commands will need to be modified to use the corresponding AIXPCM commands.”

Here’s an example of using the manage_disk_drivers  command to switch from SDDPCM to AIX PCM for a system that is using IBM SVC 2145 or DS8K disks.

a) Confirm the system is using SDDPCM for MPIO.

# manage_disk_drivers -l | grep -i svc

# manage_disk_drivers -l | grep -i 2107ds8k

IBMSVC                       NO_OVERRIDE            NO_OVERRIDE,AIX_AAPCM,non_MPIO

2107DS8K       NO_OVERRIDE     NO_OVERRIDE,AIX_AAPCM,AIX_non_MPIO

# pcmpath query device

Total Dual Active and Active/Asymmetric Devices : 2

DEV#:   3  DEVICE NAME: hdisk2  TYPE: 2145  ALGORITHM:  Load Balance

SERIAL: 60050768017F00362000000000000346  VENDOR: IBM  SIZE: 30.00 GB

==========================================================================

Path#      Adapter/Path Name          State     Mode     Select     Errors

    0*          fscsi0/path0           OPEN   NORMAL         50          0

    1           fscsi0/path1           OPEN   NORMAL       9343          0

    2*          fscsi1/path2           OPEN   NORMAL         51          0

    3           fscsi1/path3           OPEN   NORMAL       9236          0

DEV#:   4  DEVICE NAME: hdisk3  TYPE: 2145  ALGORITHM:  Load Balance

SERIAL: 60050768017F00362000000000000347  VENDOR: IBM  SIZE: 2.00 TB

==========================================================================

Path#      Adapter/Path Name          State     Mode     Select     Errors

    0           fscsi0/path0           OPEN   NORMAL        117          0

    1*          fscsi0/path1           OPEN   NORMAL         36          0

    2           fscsi1/path2           OPEN   NORMAL        121          0

    3*          fscsi1/path3           OPEN   NORMAL         36          0

The AIX PCM lsmpio command does not return anything, as SDDPCM is in control at this time.

# lsmpio -are

#

# lsdev -Cc disk

hdisk2 Available 42-T1-01 MPIO FC 2145

hdisk3 Available 42-T1-01 MPIO FC 2145

# lspath

Enabled hdisk2 fscsi0

Enabled hdisk3 fscsi0

Enabled hdisk2 fscsi0

Enabled hdisk3 fscsi0

Enabled hdisk2 fscsi1

Enabled hdisk3 fscsi1

Enabled hdisk2 fscsi1

Enabled hdisk3 fscsi1

b) Run the manage_disk_drivers command to switch to AIX PCM and reboot the system.
 

# manage_disk_drivers -d IBMSVC -o AIX_AAPCM

Or

# manage_disk_drivers -d 2107DS8K -o AIX_AAPCM

********************** ATTENTION *************************
  For the change to take effect the system must be rebooted                   

# shutdown -Fr

After the reboot, AIX PCM is now in control of MPIO on this system.

# manage_disk_drivers -l | grep -i svc

IBMSVC              AIX_AAPCM             NO_OVERRIDE,AIX_AAPCM,AIX_non_MPIO

# lsmpio -are

Adapter Driver: fscsi0 -> AIX PCM

    Adapter WWPN:  c0507607e05e0078

    Link State:    Up

    Connection Errors

    Last 10 Minutes:                          0

    Last 60 Minutes:                          0

    Last 24 Hours:                            0

    Total Errors:                             0

                               Connection Errors

                            Last 10         Last 60         Last 24

                            Minutes         Minutes         Hours

    50050768011006c4              0               0               0

    500507680110062b              0               0               0

Adapter Driver: fscsi1 -> AIX PCM

    Adapter WWPN:  c0507607e05e007a

    Link State:    Up

    Connection Errors

    Last 10 Minutes:                          0

    Last 60 Minutes:                          0

    Last 24 Hours:                            0

    Total Errors:                             0

                               Connection Errors

                            Last 10         Last 60         Last 24

                            Minutes         Minutes         Hours

    50050768011006c4              0               0               0

    500507680110062b              0               0               0

# pcmpath query device

No device file found

Now, when you’ve switched from SDDPCM to AIX PCM, you can uninstall the SDDPCM device drivers at this point.

Confirm AIX PCM is in control i.e. output from lsmpio.

# lsmpio

  name    path_id  status   path_status  parent  connection

  hdisk2  0        Enabled  Non          fscsi0  50050768011006c4,0

  hdisk2  1        Enabled  Opt          fscsi0  500507680110062b,0

  hdisk2  2        Enabled  Non          fscsi1  50050768011006c4,0

  hdisk2  3        Enabled  Sel,Opt      fscsi1  500507680110062b,0

  hdisk3  0        Enabled  Opt          fscsi0  50050768011006c4,1000000000000

  hdisk3  1        Enabled  Non          fscsi0  500507680110062b,1000000000000

  hdisk3  2        Enabled  Sel,Opt      fscsi1  50050768011006c4,1000000000000

  hdisk3  3        Enabled  Non          fscsi1  500507680110062b,1000000000000

# smit deinstall

                              Remove Installed Software

Type or select values in entry fields.

Press Enter AFTER making all desired changes.

                                                        [Entry Fields]

* SOFTWARE name   [devices.fcp.disk.ibm.mpio.rte devices.sddpcm.72.rte]                                                                     

  PREVIEW only? (remove operation will NOT occur)     yes      +

  REMOVE dependent software?                          yes      +

  EXTEND file systems if space needed?                no       +

  DETAILED output?                                             +

  FILESET STATISTICS

  ------------------

      2  Selected to be deinstalled, of which:

          2  Passed pre-deinstall verification

    ----

      2  Total to be deinstalled

  ADDITIONAL INFORMATION

  ----------------------

  One or more of the selected filesets will cause a bosboot to be performed.

  The bosboot command will rebuild the boot image.  As a result it may

  be necessary to reboot your system for the changes to take effect.

    It is recommended that you run the bosboot command to ensure success before rebooting

  It is recommended that you reboot the system as soon as possible

  after completing this task to avoid any disruption to the environment.

  Name                        Level           Part        Event       Result

  -------------------------------------------------------------------------------

  devices.sddpcm.72.rte       2.7.1.0         ROOT        DEINSTALL   SUCCESS

  devices.sddpcm.72.rte       2.7.1.0         USR         DEINSTALL   SUCCESS

  devices.fcp.disk.ibm.mpio.r 1.0.0.25        USR         DEINSTALL   SUCCESS

              

# lslpp -l | grep sddpcm

#

# pcmpath query device

 ksh: pcmpath:  not found

Additional Information

Contact the IBM Support Center to obtain assistance, or if there are questions and concerns.

Document Location

Worldwide

[{"Business Unit":{"code":"BU054","label":"Systems w\/TPS"},"Product":{"code":"ST52G7","label":"Storage software->System Storage Multipath Subsystem Device Driver"},"Component":"SDDPCM","Platform":[{"code":"PF002","label":"AIX"}],"Version":"All Versions","Edition":"","Line of Business":{"code":"","label":""}}]

Document Information

Modified date:
07 August 2020

UID

ibm11111227