Re: AIX/SAN Storage

From: Hass, Harold (HHass_at_CO.FRESNO.CA.US)
Date: 05/04/05

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    Date:         Tue, 3 May 2005 15:37:34 -0700
To: aix-l@Princeton.EDU

    You're right, it depends. On EMC, you can do WWN or Port Masking. With
    WWN masking, as long as the HBA WWN doesn't change, and you haven't
    VLAN'ed the switch, you should be OK. With Port Masking, you have to
    delete and redo the masking.

    Port Masking makes it easier to change HBAs; WWN Masking makes it easier
    to swap ports. Pick your poison.

    H. Hass

    -----Original Message-----
    From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU] On Behalf Of
    Jonathan Fosburgh
    Sent: Tuesday, May 03, 2005 1:45 PM
    To: aix-l@Princeton.EDU
    Subject: Re: AIX/SAN Storage

    On Tuesday 03 May 2005 13:53, N N wrote:
    > A single HBA AIX SAN connected system plugged into port #1 of a Fibre
    > Switch. If the fiber connection is moved from port #1 to port #2 the
    > Fiber channel D_ID (destination ID) changes. I have heard that at
    > times AIX will see the existing SAN LUNS as new hdisk devices (when
    > cfgmgr is run) because of the different D_ID. I have moved SAN ports
    > for AIX systems plenty of times and have never seen this when going to

    > a Shark or FAStT. Has anyone experienced this? EMC or IBM storage?
    >
    My experience is that IT DEPENDS(tm). If the FCID of the port changes
    then AIX will probably lose track of the devices. But, I have seen that
    turning off the system before making the move will sometimes allow the
    change to be seen and the devices will come back. Note that this has
    been inconsistent for me. Far better is to enable persistant FCIDs on
    the switch if supported, and/or enable dynamic tracking on the HBA if it
    is supported. YMMV though, persistant FCIDs is your best bet. 

    --
Jonathan Fosburgh
AIX and Storage Administrator
UT MD Anderson Cancer Center
Houston, TX
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