Re: AIX/SAN Storage
From: N N (delalist_at_HOTMAIL.COM)
Date: 05/05/05
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Date: Thu, 5 May 2005 11:57:34 -0500 To: aix-l@Princeton.EDU
That might explain it as I always use cfgmgr -vl fcs<#> instead of just
cfgmgr.
>From: Justin Bleistein <justin.bleistein@TOWERSPERRIN.COM>
>Reply-To: IBM AIX Discussion List <aix-l@Princeton.EDU>
>To: aix-l@Princeton.EDU
>Subject: Re: AIX/SAN Storage
>Date: Thu, 5 May 2005 08:56:41 -0400
>
>Correct, it's the same now.
>Thanks.
>
>--Justin Richard Bleistein
> AIX Systems Administrator
>
>
>
>
>
>
>
>Damir Delija <ddelija@PUBLIC.SRCE.HR>
>Sent by: IBM AIX Discussion List <aix-l@Princeton.EDU>
>05/05/2005 02:04 AM
>Please respond to
>IBM AIX Discussion List <aix-l@Princeton.EDU>
>
>
>To
>aix-l@Princeton.EDU
>cc
>
>Subject
>Re: AIX/SAN Storage
>
>
>
>
>
>
> > Thanks for all the feedback...
> >
> > My thoughts....
> >
>
>
>if I remeber well from my old days
>with emc critical was order in which new devices were discovered
>trough cfgmgr run. So it was essential to have
>emc_cfgmgr run instead of ordinary cfgmgr, it is a wrapper
>around cfgmgr which does sequential run over scsi, fiber
>and other adapters instead of normal paraller discovery run
>
>Sorry I can't recollect details it was about two years ago
>
>Hope this helps
>
>Damir
>
> > Unless a particular vendor does it differently part of the FC_ID is the
> > DOMAIN ID of the switch and another part is the PORT IDENTICATION #
> > (AREA).
> > Correct me if I am wrong but if you move ports the FC_ID will always
> > change
> > as the PORT IDENTIFICATION (AREA) portion of the FC_ID changes. Anyone
> > disagree?
> >
> > I can understand how this WOULD not cause new hdisk if you had the box
> > down
> > or rebooted it. I wonder if you...
> >
> > - took the paths offline in powerpath
> > - removed the paths from powerpath config
> > - rmdev -l <hdisk for particular path that is being moved>
> > - switched the ports
> > - mkdev -l <hdisk for particular path that is being moved>
> > - add back to powerpath config and turn paths on
> >
> > Basically, maybe bringing the devices associated with the path down
>BEFORE
> > making the change would prevent new hdisks from being created. That
>would
> > be compared to just moving the cable on the fly and letting powerpath
> > handle
> > all of the path failure detection and reactivation.
> >
> > Sounds like the people who repsonded have had different results. There
>has
> > to be some factor that caused new hdisks to get created one time and not
> > another.
> >
> > The reason I thought maybe the storage type makes a difference is
>because
> > depending on the driver, disk type and presentation method the
>attributes
> > under lsattr and lscfg for a LUN (hdisk) can be different. (Example
>would
> > be Shark LUNS vs SVC Virtualized LUNS) If one of the attributes changed
> > when
> > moving ports that may cause the new hdisks to get created. Since I had
> > heard of this happening primarily with EMC storage I thought maybe the
>LUN
> > definition in AIX is different for IBM disks vs. EMC disks. Has anybody
> > had
> > this happen with IBM storage or were the references strictly for EMC
> > storage?
> >
> >
> >>From: jeff barratt-mccartney <jbarratt@COMPSAT.COM>
> >>Reply-To: IBM AIX Discussion List <aix-l@Princeton.EDU>
> >>To: aix-l@Princeton.EDU
> >>Subject: Re: AIX/SAN Storage
> >>Date: Wed, 4 May 2005 08:35:38 -0400
> >>
> >>neither of these options refer to FC_ID.nor does the storage device make
> >> a
> >>significant difference.
> >>
> >>hard and soft zoning, and VLANing have no affect on FC_ID. Since you
> >>mention
> >>VLAN, then you have cisco switches, which allows you to maintain a
> >>persistent FCID, making this argument a moot point in that environment.
> >>
> >>my experience is the same as jonathon's, there seems to be no hard and
> >> fast
> >>guarantee that FC_ID will not change when moving across ports/switches.
> >>Does
> >>anyone out there have conflicting information?
> >>
> >>
> >>-----Original Message-----
> >>From: IBM AIX Discussion List [mailto:aix-l@Princeton.EDU]On Behalf Of
> >>Hass, Harold
> >>Sent: Tuesday, May 03, 2005 6:38 PM
> >>To: aix-l@Princeton.EDU
> >>Subject: Re: AIX/SAN Storage
> >>
> >>
> >>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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>
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