[linux-lvm] Re: alternate link / multi-pathing

C'est Pierre cestpierre at gmail.com
Sun May 28 14:35:38 UTC 2006

Hello Luca,

Thanks for pointing me that out, too bad it's a bit late, since the
server is now crashed and only tomorrow I will be able to reset it.
Meanwhile, I've got a few questions for you:

1. How do I disable raid autodetect ?
2. Where can I read about device-mapper-multipath ?
3. To deactivate the vg, I suppose I should use vgchange -a n, correct
me if I am wrong

Thank you for your reply!

On 5/28/06, Luca Berra <bluca at comedia.it> wrote:
> On Sun, May 28, 2006 at 02:50:24AM +0100, C'est Pierre wrote:
> >Nevermind about my previous question! I just made my way into this
> >page:
> >http://www.redhat.com/docs/manuals/enterprise/RHEL-4-Manual/s390-multi-install-guide/s1-s390info-raid.html
> >and have setup the multipathing nicely.
> actually the device-mapper-multipath would a better approach than
> md-multipath
> >However, I went into the second node (this is 2 nodes failover cluster
> >environment) and I noticed that the vg and the md0 appeared there
> >there automatically! is this normal? is there anything I should do?
> it is not normal
> it should not happen
> if you insist in using md multipath, ensure raid autodetect won't pick
> it up.
> i.e. disable damned autodetect on kernel command line or
> change the partition type to something different than 'Linux Raid'
> then you'll have to ensure that your distribution  init scripts do not
> automatically start it.
> best way is omitting this set entries from /etc/mdadm.conf
> and putting it somewhere else, then invoking
> "mdadm -Asc /some/where/else/mdadm.conf" in your cluster script
> if you use device-mapper-multipath (which might also solve the issue in
> your next post :)
> there is no problem if multipath finds the devices on the failover node,
> but you must prevent lvm from activating the vg
> to do this either add cluster locking or use tags, as explained in the
> doc/tagging.txt files in the lvm distribution
> Regards,
> L.
> --
> Luca Berra -- bluca at comedia.it
>         Communication Media & Services S.r.l.
>  /"\
>  / \
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