PowerPath for AIX : Following an NDM migration,the file system is mounted in Read-Only mode

           

   Article Number:     498410                                   Article Version: 4     Article Type:    Break Fix 
   

 


Product:

 

Solutions Enabler 8.1,Solutions Enabler 8.2,Solutions Enabler 8.3,PowerPath for AIX,VMAX3 Series

 

Issue:

 

 

Environment :   
    DELL EMC SW : NDM for hyper VMAX   
    DELL EMC SW : Powerpath for AIX   
    DELL EMC array : VMAX running 5977 code or above   
    OS : AIX 6.x, AIX 7.x   
   
    Following a NDM migration of rootvg, "/" is mounted in Read-Only mode after the cutover   
   
    <my_server>df   
    ksh: The file system has read permission only.   
    Filesystem    512-blocks      Free %Used    Iused %Iused Mounted on   
    /dev/hd4         4194304   3544688   16%    11943     3% /   
    /dev/hd2        10485760   5534144   48%    51552     8% /usr   
    /dev/hd9var      4194304   2079720   51%    11011     5% /var   
    /dev/hd3         6291456   3119384   51%      883     1% /tmp   
    /dev/hd1         2097152   1098064   48%     2771     3% /home   
    /dev/hd11admin    1048576   1047696    1%        9     1% /admin   
    /proc                  -         -    -         -     -  /proc   
    /dev/hd10opt     2097152   1590752   25%     7284     4% /opt   
    ...   
    <my_server>touch /tmp/abc   
    ksh: The file system has read permission only.       
        ksh: touch: 0403-006 Execute permission denied.​
   
    <my_server>   
     
                                                           

 

 

Cause:

 

 

As per Appendix B of VMAX NON-DISRUPTIVE MIGRATION document, properly configuring multiple paths to the host with AIX 6.x, [AIX 7.x}, GPFS, and PowerPath requires an additional step when performing an NDM migration.   
   
    After the NDM create operation is completed, the target devices (appearing to the host as additional paths to the source devices) will be masked and available. After running cfgmgr to create the host native devices, the [attached] script, named emc_pp_configure.sh, must be run immediately following the completion of the cfgmgr command. The script will configure the new native devices on the target side into PowerPath by copying the attributes of the PowerPath hdiskpower pseudo devices into the new native devices and reconfigure the native devices.   
   
    Note: This script MUST be used in order to perform a migration non-disruptively in this environment. Failing to run the script following the configuration of the new native target devices can lead to data unavailability.   
   
    #! /bin/ksh   
    devlist=`powermt config 2>&1 | grep -p 0514-034 | grep hdiskpower | awk '{print $5}'`   
    for pseudo in $devlist   
    do   
        pseudo_policy=`lsattr -El $pseudo -a reserve_policy | awk '{print $2}'`   
        pseudo_prkey=`lsattr -El $pseudo -a PR_key_value | awk '{print $2}'`   
        nativelist=`powermt display dev=$pseudo | grep -i hdisk| grep -v power | awk '{print $3}'`   
        echo $nativelist   
        for native in $nativelist   
        do   
            native_policy=`lsattr -El $native -a reserve_policy | awk '{print $2}'`   
            native_prkey=`lsattr -El $native -a PR_key_value | awk '{print $2}'`   
    #change reserve_policy and PR_key_value of native(s), whose policy or PR_key_value   
    #vary from that of pseudo.   
            if [[ $native_policy != $pseudo_policy || $native_prkey != pseudo_prkey ]]   
            then   
                powermt remove dev=$native   
                echo changing reserve_policy,PR_key_value of $native to $pseudo_policy and $pseudo_prkey   
                chdev -l $native -a reserve_policy=$pseudo_policy -a PR_key_value=$pseudo_prkey     
            fi   
        done   
    done   
    powermt config   
   
   
    The script, emc_pp_configure.sh, can be downloaded on EMC‟s support site :https://support.emc.com/search/?text=powerpath&facetResource=ST&facetProductId=1726
                                                           

 

 

Change:

 

 

NDM is used to migrate an AIX Powerpath pseudo devices.                                                            

 

 

Resolution:

 

 

After the NDM create operation is completed, run a "cfgmr" to discover the new path to the devices, followed by a "powermt config". Run the EMC provided script "emc_pp_configer.sh" script.   
   
    If the migration involves rootvg, update the bootlist to include the new hdisks pointing to the target array. If needed, run a "pprootdev fix",and run a "bosboot -ad /dev/ipldevice" to update the boot disk.   
   
    These steps are needed after completion of the NDM create command (symdm create).
                                                           

 

 

Notes:

 

 

Following the migration, the devices will appear as if they were still attached to the source array (S/N of the array is unchanged; VMAX volumeID is unchanged). This is expected since it is part of the NDM magic which must be as transparent as possible for the host. Changing the identity of the device would be an offline change.