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

Roberto Fratelli robertofratelli at yahoo.com
Mon Apr 27 17:09:46 UTC 2009


Hi Stevan,

I saw this in some examples, but somehow it just don't work for me :

# /sbin/scsi_id -g -s /block/emcpowerf
Cannot find sysfs device associated with /sys/block/emcpowerf
#



Weird.. A guy from EMC just sent me something that will fit just perfect. I'll share with the entire list.

Regards,


--- On Mon, 4/27/09, Stevan Colaco <stevan.colaco at gmail.com> wrote:

> From: Stevan Colaco <stevan.colaco at gmail.com>
> Subject: Re: [Linux-cluster] Persistent naming with UDEV and EMC's Powerpath
> To: "linux clustering" <linux-cluster at redhat.com>
> Date: Monday, April 27, 2009, 8:52 AM
> Hello,
> 
> There are different ways one may write the persistent
> naming udev rules.
> 
> Instead of SYSFS{serial}, it would be better if you can use
> scsi_id
> 
> first try to get the scsi id of the quorum device
> 
> #/sbin/scsi_id -g -s /block/emcpowerf
> 
> you should receive a lengthy number. 
> 
> Then you can use the rule something like below 
> 
> [root at node-a RSM]# cat 75-quorum.rules
> KERNEL=="emcpower[a-z]1, PROGRAM=="/sbin/scsi_id -g -s
> /block/emcpowerf", RESULT=="Paste the output of scsi_id
> here" SYMLINK+="discodequorum"
> 
> 
> regards,
> -Steve
> 
> [root at node-a RSM]#
> 
> ----- Original Message -----
> From: "Roberto Fratelli" <robertofratelli at yahoo.com>
> To: linux-cluster at redhat.com
> Sent: Monday, April 27, 2009 4:17:47 PM GMT +03:00 Iraq
> 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 at 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 at 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 at node-a RSM]# cat 75-quorum.rules
> KERNEL=="emcpower[a-z]1,
> SYSFS{label}=="97196ef0-da2f-4b79-a5c5-999dce70d677",
> SYMLINK+="discodequorum%n"
> [root at 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 at 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 at node-a:~ #
> 
> 
> 
> [root at 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 at node-b ~]#
> 
> 
>       
> 
> --
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> 
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