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Re: [Linux-cluster] mounting a replicated lun

It a LVM2 lun.

I have presened both luns to a node. Below mpath2 refers to original lun and mapth5 is a replicated lun. both luns are identical. What I need to do is remove mpath2 and use only mpath5. I am still confused what are the steps i need to do to achieve this. I can't do pvcreate  or mkfs.gfs2 I know this.

[root cvtst3 ~]# multipath -ll
mpath2 (36000d310002f1c00000000000000001b) dm-4 COMPELNT,Compellent Vol
[size=100G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 1:0:4:1 sde 8:64  [active][ready]
 \_ 1:0:5:1 sdf 8:80  [active][ready]
 \_ 4:0:4:1 sdi 8:128 [active][ready]
 \_ 4:0:5:1 sdj 8:144 [active][ready]
mpath5 (36000d310002fb000000000000000002b) dm-3 COMPELNT,Compellent Vol
[size=100G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=1][active]
 \_ 1:0:2:1 sdc 8:32  [active][ready]
 \_ 1:0:3:1 sdd 8:48  [active][ready]
 \_ 4:0:2:1 sdg 8:96  [active][ready]
 \_ 4:0:3:1 sdh 8:112 [active][ready]

Here is the output of pvs if needed. It says duplicate pvs . I am assuming it sees the lvm label(?)

[root cvtst3 ~]# pvs
  Found duplicate PV 0zbIvXwSZbfjD8Pg2KdqvgcHka30P2Ve: using /dev/mpath/36000d310002f1c00000000000000001bp2 not /dev/mpath/36000d310002fb000000000000000002bp2
  PV                                             VG         Fmt  Attr PSize  PFree  
  /dev/mpath/36000d310002f1c00000000000000001bp2 guest_vg_c lvm2 a--  99.97G 996.00M
  /dev/sda2                                      VolGroup00 lvm2 a--  67.84G      0 


On Thu, Nov 21, 2013 at 4:24 AM, Bryn M. Reeves <bmr redhat com> wrote:
On 11/20/2013 10:29 PM, Paras pradhan wrote:
> Since the luns are same in all aspects, will it automatically configure
> itself the new one and mount it to /test?

As far as mounting goes (this is the same for any file system) it will
depend on how the LUN was configured and used in the first place.

If you're using something like LVM2 which identifies a device by a label
written to the disk itself then the system will find it and activate
whatever volume groups it contains regardless of the device name or
identifier (WWID).

If you're using plain multipath or bare devices on the other hand then
the device WWID will be different for the original LUN vs. the
replicated one. This will cause SCSI or multipath device names to change
and if those are used in fstab, scripts or cluster configuration files
then the device will not mount without manual changes to update that

I'm not expert in gfs2 and cluster specifics so you'll need to consider
Bob's advice as well to ensure you get a correct set up for the new
device (and have it consistent across the cluster).


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