Creation of the mpath# devices

Creation of the mpath# devices

[Scott Moseman]

I guess my problems are never completely eliminated... :)

Setup device-mapper multipathing in RHEL 4
http://kbase.redhat.com/faq/FAQ_51_7170.shtm

Per the above KB, after the multipath daemon is configured and
started, "The multipath -v2 command prints out multipathed paths that
show which devices are multipathed. If the command does not print
anything out, ensure that all SAN connections are set up properly and
the system is multipathed."

# multipath -v2

I get nothing on my server.  Although here's what I do get.

# multipath -l
30690a018f015191a6472441d1500f057
[size=4 GB][features="0"][hwhandler="0"]
\_ round-robin 0 [active]
 \_ 3:0:0:0 sdc 8:32 [active][ready]
\_ round-robin 0 [enabled]
 \_ 1:0:1:0 sdb 8:16 [active][ready]

# multipath -v3
--- snipped ---
#
# all paths in cache :
#
30690a018f015191a6472441d1500f057  1:0:1:0 sdb 8:16  [active][ready] EQLOGIC /
30690a018f015191a6472441d1500f057  3:0:0:0 sdc 8:32  [active][ready] EQLOGIC /
hda blacklisted
sda blacklisted
--- snipped ---

What am I missing?  As far as I can tell, I'm following the RHEL KB
perfectly and it's still not working as expected (although now I'm
much farther than before!).

Thanks!
Scott

Re: Creation of the mpath# devices

[Benjamin Marzinski]

On Thu, Nov 15, 2007 at 03:02:45PM -0600, Scott Moseman wrote:
> I guess my problems are never completely eliminated... :)
> 
> Setup device-mapper multipathing in RHEL 4
> http://kbase.redhat.com/faq/FAQ_51_7170.shtm
> 
> Per the above KB, after the multipath daemon is configured and
> started, "The multipath -v2 command prints out multipathed paths that
> show which devices are multipathed. If the command does not print
> anything out, ensure that all SAN connections are set up properly and
> the system is multipathed."
> 
> # multipath -v2
> 
> I get nothing on my server.  Although here's what I do get.
> 
> # multipath -l
> 30690a018f015191a6472441d1500f057
> [size=4 GB][features="0"][hwhandler="0"]
> \_ round-robin 0 [active]
>  \_ 3:0:0:0 sdc 8:32 [active][ready]
> \_ round-robin 0 [enabled]
>  \_ 1:0:1:0 sdb 8:16 [active][ready]
> 
> # multipath -v3
> --- snipped ---
> #
> # all paths in cache :
> #
> 30690a018f015191a6472441d1500f057  1:0:1:0 sdb 8:16  [active][ready] EQLOGIC /
> 30690a018f015191a6472441d1500f057  3:0:0:0 sdc 8:32  [active][ready] EQLOGIC /
> hda blacklisted
> sda blacklisted
> --- snipped ---
> 
> What am I missing?  As far as I can tell, I'm following the RHEL KB
> perfectly and it's still not working as expected (although now I'm
> much farther than before!).

If you were only expecting to have /dev/sdb and /dev/sdc multipathed,
then you are fine.  The problem is in the Knowledge Base article.

# multipath -v2

only prints out the multipath maps that it creates.  If, as in your
case, the map already exists, it should print nothing.

# multipath -l

prints out all the existing multipath devices.
You should see the device node

/dev/mapper/30690a018f015191a6472441d1500f057

and the symbolic link

/dev/mpath/30690a018f015191a6472441d1500f057

Which you can use to access the device. If you don't like dealing with
such a cumbersome name, you can always add

      user_friendly_names yes

to the defaults section of /etc/multipath.conf

-Ben
 
> Thanks!
> Scott
> 
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel

Re: Creation of the mpath# devices

[Scott Moseman]

On Nov 15, 2007 3:29 PM, Benjamin Marzinski <bmarzins@redhat.com> wrote:
>
> Which you can use to access the device. If you don't like dealing with
> such a cumbersome name, you can always add
>
>       user_friendly_names yes
>
> to the defaults section of /etc/multipath.conf
>

Hey Ben,

That worked great.  :)  I now have /dev/mapper/mpath0 (and the p1
partition that already exists) and it's now officially mounted and
working!  Is there any "best practices" about whether I should be
mounting the /dev/mapper/mpath0p1 or /dev/mpath/mpath0p1 device?

Thanks,
Scott

Re: Creation of the mpath# devices

[Kevin Foote]

/dev/mapper/<your dev>

I believe...

What does your output of this command show.. just currious as I have
multiple devices on
an equallogic and I'm trying to figure out an issue with multipath
thinking the path is down when its not..

command => dmsetup table /dev/mapper/<yourdevice>

-- 
:wq!
kevin.foote

On Nov 15, 2007 5:36 PM, Scott Moseman <scmoseman@gmail.com> wrote:
> On Nov 15, 2007 3:29 PM, Benjamin Marzinski <bmarzins@redhat.com> wrote:
> >
> > Which you can use to access the device. If you don't like dealing with
> > such a cumbersome name, you can always add
> >
> >       user_friendly_names yes
> >
> > to the defaults section of /etc/multipath.conf
> >
>
> Hey Ben,
>
> That worked great.  :)  I now have /dev/mapper/mpath0 (and the p1
> partition that already exists) and it's now officially mounted and
> working!  Is there any "best practices" about whether I should be
> mounting the /dev/mapper/mpath0p1 or /dev/mpath/mpath0p1 device?
>
>
> Thanks,
> Scott
>
> --
> dm-devel mailing list
> dm-devel@redhat.com
> https://www.redhat.com/mailman/listinfo/dm-devel
>

Re: Creation of the mpath# devices

[Scott Moseman]

On Nov 16, 2007 7:55 AM, Kevin Foote <kevin.foote@gmail.com> wrote:
>
> What does your output of this command show.. just currious as I have
> multiple devices on an equallogic and I'm trying to figure out an issue
> with multipath thinking the path is down when its not..
>
> command => dmsetup table /dev/mapper/<yourdevice>
>

For what it's worth...

# dmsetup table /dev/mapper/mpath0
0 8417280 multipath 0 0 2 1 round-robin 0 1 1 8:32 100 round-robin 0 1
1 8:16 100

Thanks,
Scott