The Question is:
I am connecting 2 different storage arrays to one OVMS AlphaServer through an
FC switch. The CU and LDEV numbers are used to create a 'DG' device name at
the OS level. I have an application that uses similarly configured arrays
(same CU and LDEV numbers
) in each array.
My problem is that when I have multipath running (MPDEV_ENABLE), the DG device
name resolves as having 2 different paths to the device. It is true that 2
different paths exist to the same device name, but, in this case, they are not
the same device, they
are on different arrays that may not have the same data on them.
When I disable multipath, only 1 DG device shows up. It is not clear to me
which device that is, as the complete path with WWN is not shown at the SHOW
Can I tailor OVMS to recognize these 2 devices as being different, even they
have the same CU and LDEV number?
The Answer is :
The OpenVMS Fibre Channel device drivers and the associated code
supplied with OpenVMS will not produce the symptoms described,
when used with a correctly-functiong and correctly-configured HSG
series storage controller.
Details of the hardware and software and firmware involved here will
be required. Please contact the Compaq Customer Support Center.
OpenVMS depends on the user-selected unit identification value set
in the Fibre Channel Storage Controller to assign the device name,
and all Fibre Channel devices present and configured are all assumed
to be named $1$DGA[identifier]:
At the Storage Controller:
HSG> set unit d17 identifier=1234
To enable the visibility of the device to the Alpha SRM console:
P00>>> set mode diag
P00>>> wwidmgr -quickset -udid 1234
P00>>> show device
The identifier is returned via a SCSI command in the vendor-specific
command set unique to the HSG series storage controllers.
There is an allocation class setting in various Fibre Channel
controllers, but OpenVMS does not use this value -- OpenVMS assigns
all Fibre Channel disk devices into allocation class one.
The OpenVMS Alpha Fibre Channel disk configuration process is
separate from the Alpha SRM console console wwigmgr setting.
Details on Fibre Channel configuration and operation are available
in the Fibre Channel documentation at the OpenVMS website. (A direct
URL to this portion of the website is listed in the OpenVMS FAQ.)