[Linux-cluster] mounting a replicated lun

[Paras pradhan]

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 at 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 at 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
----


Thanks
Paras.


On Thu, Nov 21, 2013 at 4:24 AM, Bryn M. Reeves <bmr at 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
> configuration.
>
> 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).
>
> Regards,
> Bryn.
>
>
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