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RE: [Linux-cluster] Persistent naming with UDEV and EMC's Powerpath



Hi Roberto.

	It won't hurt to do it and would be advisable.

Regards,
Wayne. 

-----Original Message-----
From: linux-cluster-bounces redhat com [mailto:linux-cluster-bounces redhat com] On Behalf Of Roberto Fratelli
Sent: Monday, April 27, 2009 1:00 PM
To: linux clustering
Subject: RE: [Linux-cluster] Persistent naming with UDEV and EMC's Powerpath


Excellent ! thanks a million ! this emcpadm command was unknown to me. I just tested it and works great ! 

Just another question: Is it necessary to issue 'powermt save' after renaming the pseudo-devices ?

Regards,

Roberto



--- On Mon, 4/27/09, berthiaume_wayne emc com <berthiaume_wayne emc com> wrote:

> From: berthiaume_wayne emc com <berthiaume_wayne emc com>
> Subject: RE: [Linux-cluster] Persistent naming with UDEV and EMC's Powerpath
> To: linux-cluster redhat com
> Date: Monday, April 27, 2009, 9:43 AM
> Hi Roberto.
> 
>      You can use the emcpadm()
> command to rename the device on each
> node so they are all the same. The syntax is "emcpadm
> rename[pseudo] -s
> src pseudodevice -t tgt pseudodevice". For example, if on
> node A the
> device is emcpowerg and you wish it to be be emcpowerq you
> would issue:
> 
> # emcpadm rename -s emcpowerg -t emcpowerq 
> 
>     For each node run the "powermt display
> dev=all" and review the
> Logical device ID that is displayed for each LUN on each
> node. Find your
> quorom disk on each - for example, Logical device
> ID=6006016018C80800B5069570B8A9D911
> 
> # powermt display dev=emcpowerg
> 
> Pseudo name=emcpowerg
> CLARiiON ID=WRE00100100415
> Logical device ID=6006016018C80800B5069570B8A9D911
> state=alive; policy=CLAROpt; priority=0; queued-IOs=0
> Owner: default=SP A, current=SP A
> ======================================================================
> ------------ Host ----------- - Stor - -- I/O Path - --
> Stats ---
> ### HW Path I/O Paths Interf. Mode State Q-IOs Errors
> ======================================================================
> 3 lpfc sdaa SP A0 active alive 0 0
> 2 lpfc sdj SP A1 active alive 0 0
> 
> Then rename it....
> 
> # emcpadm rename -s emcpowerg -t emcpowerq 
> 
> ...and your in business.
> 
> Regards,
> Wayne.
> 
> -----Original Message-----
> From: linux-cluster-bounces redhat com
> [mailto:linux-cluster-bounces redhat com]
> On Behalf Of Roberto Fratelli
> Sent: Monday, April 27, 2009 9:18 AM
> To: linux-cluster redhat com
> Subject: [Linux-cluster] Persistent naming with UDEV and
> EMC's Powerpath
> 
> 
> Hello everyone !
> 
> I'm trying to set up a quorum disk in a 2-node redhat
> cluster (RHEL
> 4.7). Both nodes are attached to a SAN Clariion over qlogic
> HBA's and
> i'm using EMC's powerpath.
> 
> The problem i'm facing is that the disks's device names are
> different
> across the nodes. For example, the lun i elected to be my
> quorum disk is
> called '/dev/emcpowerf' at node-a and '/dev/emcpowerd' at
> node-b, so i
> can't use the device name (/dev/emcpowerXX) in my
> cluster.conf file. In
> a attempt to overcome this i've tried to use the disk label
> instead :
> 
> <quorumd label="97196ef0-da2f-4b79-a5c5-999dce70d677"
> interval="2"
> tko="10" votes="1"/>
> 
> But did not work also, because this way it finds
> '/dev/sdXX' before
> '/dev/emcpowerXX':
> 
> root node-a:~ # cman_tool nodes
> Node  Votes Exp Sts  Name
>    0    1   
> 0   M   /dev/sdf1
>    1    1   
> 2   M   node-a
>    2    1   
> 2   M   node-b
> root node-a:~ #
> 
> 
> Since this '/dev/sdf' is just one of the paths i have under
> powerpath
> (it has 4 paths per HBA, 8 paths per lun total) i can't
> keep it this way
> because in a event of lun trespass (clariion does it very
> often) i would
> loose quorum. My understanding is that i need some kind of
> "persistent
> binding" so i can use Powerpath's pseudo-device
> '/dev/emcpowerXX', so i
> tried to create a UDEV rule like this:
> 
> [root node-a RSM]# cat 75-quorum.rules
> KERNEL=="emcpower[a-z]1,
> SYSFS{label}=="97196ef0-da2f-4b79-a5c5-999dce70d677",
> SYMLINK+="discodequorum%n"
> [root node-a RSM]#
> 
> 
> Which did not worked, i think because UDEV starts way
> before powerpath.
> Does anyone here faced this problem before ? how can i keep
> the device
> names persistent across the nodes (at least for the quorum
> disk) ?
> 
> 
> Below some more info on my quorum's disk:
> 
> 
> root node-a:~ # mkqdisk -L
> mkqdisk v0.5.2
> /dev/sdf1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdo1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdx1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdag1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdap1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sday1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdbh1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdbq1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/emcpowerf1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> root node-a:~ #
> 
> 
> 
> [root node-b ~]# mkqdisk -L
> mkqdisk v0.5.2
> /dev/sdf1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdo1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdx1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdag1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdap1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sday1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdbh1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/sdbq1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> /dev/emcpowerd1:
>         Magic:     
>           eb7a62c2
>         Label:     
>          
> 97196ef0-da2f-4b79-a5c5-999dce70d677
>         Created:     
>         Mon Dec 24 11:47:11 2007
>         Host:     
>            node-a
>         Kernel Sector
> Size:   512
> 
> [root node-b ~]#
> 
> 
>       
> 
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> 
> 
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> 


      

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