Multiple paths not observed using HP PSP QLA2xxx drivers

This document (7004224) is provided subject to the disclaimer at the end of this document.

Environment

SUSE Linux Enterprise Server 10 Service Pack 2

Situation

HP Proliant Support Pack V 7.90-8.25
NetApp San Storage

After installing HP PSP V 7.90, admin observed that the command of"mulitpath -ll" only shows one path. The storage is configured for four paths. The QLogic sCLI Management Application shows four paths,

--------------------------------------------------------------------------------
HBA Instance 0: QMH2462 Port 1 WWPN 50-01-43-80-02-AF-BF-7C PortID 64-07-00
--------------------------------------------------------------------------------
Target WWPN 50-0A-09-86-87-D9-37-BF PortID 61-00-37
------------------------------------------------------------
Product Vendor    : NETAPP
Product ID    : LUN
Product Revision    : 0.2
LUN       : 1
Size       : 250.00 GB
Type       : SBC-2 Direct access block device
      (e.g., magnetic disk)
WWULN      : 4E-45-54-41-50-50-20-20-20-4C-55-4E-20-48-6E-53
     50-2F-6F-4F-4D-56-66-5A-2F-00-00-00-00-00-00-00
OS LUN Name    : /dev/sda;/dev/sg1;
------------------------------------------------------------
Target WWPN 50-0A-09-87-97-D9-37-BF PortID 61-00-38
------------------------------------------------------------
Product Vendor    : NETAPP
Product ID    : LUN
Product Revision    : 0.2
LUN       : 1
Size       : 250.00 GB
Type       : SBC-2 Direct access block device
      (e.g., magnetic disk)
WWULN      : 4E-45-54-41-50-50-20-20-20-4C-55-4E-20-48-6E-53
     50-2F-6F-4F-4D-56-66-5A-2F-00-00-00-00-00-00-00
OS LUN Name    :
------------------------------------------------------------
Target WWPN 50-0A-09-84-87-D9-37-BF PortID 61-00-39
------------------------------------------------------------
Product Vendor    : NETAPP
Product ID    : LUN
Product Revision    : 0.2
LUN       : 1
Size       : 250.00 GB
Type       : SBC-2 Direct access block device
      (e.g., magnetic disk)
WWULN      : 4E-45-54-41-50-50-20-20-20-4C-55-4E-20-48-6E-53
     50-2F-6F-4F-4D-56-66-5A-2F-00-00-00-00-00-00-00
OS LUN Name    :
------------------------------------------------------------
Target WWPN 50-0A-09-85-97-D9-37-BF PortID 61-00-3A
------------------------------------------------------------
Product Vendor    : NETAPP
Product ID    : LUN
Product Revision    : 0.2
LUN       : 1
Size       : 250.00 GB
Type       : SBC-2 Direct access block device
      (e.g., magnetic disk)
WWULN      : 4E-45-54-41-50-50-20-20-20-4C-55-4E-20-48-6E-53
     50-2F-6F-4F-4D-56-66-5A-2F-00-00-00-00-00-00-00
OS LUN Name    :

NetApp's sanlun util only shows one path. When checking the modprobe.conf.local, the correct parms where present:

options qla2xxx ql2xmaxqdepth=16 qlport_down_retry=64 ql2xloginretrycount=16 ql2xfailover=0 ql2xlbType=0 ql2xautorestore=0x0

Resolution

HP's qlogic drivers do not operate the same as the Suse qlogic modules. They handle multipathing on the driver level, and the additional paths are hidden from the OS. The parm that enables/disables this feature is:

ql2xfailover=0

In this issue, the modprobe.conf.local does have this feature disabled, yet the driver still has the appearance of hiding the additional paths to the OS. Adding "qla2xxx.ql2xfailover=0" to the kernel boot parms allowed all paths to appear to the os tools. This problem was due to the module install into the kernel image. Is was compiled with the value of

ql2xfailover=1

This overrides the any value in the /etc/modprobe.conf.local. The issue can be resolved per HP documentation

Changing Driver Parameters

You can change the parameters of the driver using the set_parm script in
either the /opt/hp/src/hp_qla2x00src directory or the /opt/hp/hp_qla2x00
directory (depending upon which RPM you have installed). There are three
preset settings:

1. Single Path (-s)     you are connected through one path to the storage
                        without any redundancy
2. Secure Path (-m)     you are using the Secure Path software for multipathing
                        and failover
3. QLogic Failover (-x) you are using the multipathing and failover
                        functionality built into the qla2x00 adapter driver

You can also manually set the driver parameters if you invoke set_parm with
no arguments and select the manual option from the menu.

Note that if you change the driver parameters, a new initrd has to be build.
This is done by the set_parm script by calling the edit_conf and make_initrd
scripts.

It must also be noted, that the SuSE multipathd should not be used if you choose to use the multipathing function in the HP supplied Qlogic modules.

SUSE strongly recommends that you use the Qlogic drivers supplied with the distribution. This removes the problems associated with kernel updates and 3rd party drivers.

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