Disabling MPIO on AIX Platform

Article:HOWTO21854  |  Created: 2010-01-28  |  Updated: 2011-06-01  |  Article URL http://www.symantec.com/docs/HOWTO21854
Article Type
How To


Environment


 
Disabling MPIO
The Multiple Path I/O (MPIO) feature was introduced in AIX 5.2 to manage disks and LUNs with multiple paths. By default, MPIO is enabled on all disks and LUNs that have this capability, which prevents DMP or other third-party multipathing drivers (such as EMC PowerPath) from managing the paths to such devices.
To allow DMP or a third-party multipathing driver to manage multipathing instead of MPIO, you must install suitable Object Data Manager (ODM) definitions for the devices on the host. Without these ODM definitions, MPIO consolidates the paths, and DMP can only see a single path to a given device.
There are several reasons why you might want to configure DMP to manage multipathing instead of MPIO:
 
  • Using DMP can enhance array performance if an ODM defines properties such as queue depth, queue type and timeout for the devices.
 
  • The array fencing features of the Storage Foundation HA or Storage Foundation Real Application Cluster software do not work with MPIO devices.
 
 
How to get ODM definition from Array vendor:
 
 
Array Vendor ODM definition location
EMC ftp://ftp.emc.com/pub/elab/aix/ODM_DEFINITIONS/
IBM http://www-01.ibm.com/support/docview.wss?rs=540&uid=ssg1S4000106
Hitachi https://tuf.hds.com/gsc/bin/view/Main/AIXODMUpdates
 
For Other Array vendors for which the download links are not listed , please directly contact the array vendor's support to get the latest ODM definitions.
 
. The ODM definition should permit either DMP or the array vendors multi-pathing driver to discover the devices in the supported array.
Having obtained the packages that contain the new ODM definitions, use the following procedure to configure DMP or an array vendor8217s multipathing driver in place of MPIO.
To disable MPIO
1. Unmount any file systems and stop all applications such as databases that are configured on VxVM volumes.
2. Stop all I/O to the VxVM volumes by entering the following command for each disk group:
# vxvol -g diskgroup stopall
3. Use the vxprint command to verify that no volumes remain open:
# vxprint -Aht -e v_open
4. Deport each disk group in turn:
# vxdg deport diskgroup
5. Use the following command to remove each hdisk device that MPIO has configured to the arrays:
# rmdev -dl hdisk_device
sometime rmdev failed with following erroe messages
eg)
# rmdev -dl hdisk_device
Method error (/usr/lib/methods/ucfgdevice):
       0514-062 Cannot perform the requested function because the
                specified device is busy.
In this case remove the disk from volume manager control as below;
# vxdisk rm <dm name of the above hdisk>
then
# rmdev -dl hdisk_device
 
Alternatively, use the smitty rmdev command.
6. Use the installp command to install the replacement ODM packages:
# install - agXd ODM_package ...
Alternately, you can use the smitty installp command.
7. Reboot the system so that the new ODM definitions are used to perform device discovery.
8. Use the vxdmpadm command to check that DMP now has access to all the paths to the devices. The following command displays a list of HBA controllers that are configured on a system:
# vxdmpadm listctlr all
The next command displays information about all the paths that are connected to a particular HBA controller (for example, fscsi2):
# vxdmpadm getsubpaths ctlr=controller

Legacy ID



341102


Article URL http://www.symantec.com/docs/HOWTO21854


Terms of use for this information are found in Legal Notices