[Ocfs2-users] CDSL .vs. Bind mounts?

[Marc Grimme]

As we are making shareing the "/"-Filesystem among multiple nodes we are using 
CDSL as part of the concept.
What we do is we create 
<mount-point>/cluster/<nodeid>
<mount-point>/cdsl.local -> /cluster/nodeid (via bind mount)

Then say you would like to make /opt/application/file1 hostdependent do the 
following
mkdir -p /cluster/cdsl/[1-n]/$(dirname /opt/application/file) 
cp -a 
<mount-point>/opt/application/file /cluster/cdsl/[1-n]/$(dirname /opt/application/file)
ln -s <mount-point>/opt/application/file 
<mount-point>/cdsl.local/opt/application/file

That's it and it works pretty well.
Hope this helps.
This concept keeps all file that are hostdep and reshared 
in /cluster/cdsl/.. .
Regards
Marc.

BTW: We've also developed tools to manage those cdsls.
Those are based on the syntax for the Tru64-Cluster cdsl tools.
i.e. com-mkcdsl -a /opt/application/file1 (-a => hostdependent)

See www.open-sharedroot.org.
On Tuesday 22 September 2009 23:15:07 John McNulty wrote:
> I'm puzzled.  Coming from a Tru64/TruCluster background I know CDSL's
> well, but have never used bind mounts.  From reading about them it
> looks to me like:
>
>      a CDSL = [one] file that points to [many] files, but
>      a bind mount = [many] mount points that originate from [one]
>
> Not only is the one to many relationship of a bind mount the opposite
> of a CDSL, but it's not possible to replace  [for example] a CDSL
> like /etc/application.conf by mounting something on top of it.
>
> How is this supposed to work?
>
> Rgds,
>
> John
>
> On 17 Sep 2009, at 16:33, David Johle wrote:
> > At 02:00 PM 5/5/2009, ocfs2-users-request at oracle.com wrote:
> >>        The mainline linux kernel developers have decided that CDSLs
> >> are
> >> not something they will accept.  As such, ocfs2 in mainline does not
> >> support them, and production ocfs2 1.4 and later do not either.
> >>        The recommended solution from the kernel developers is bind
> >> mounts.  You can set those up on your own system via startup scripts.
> >>
> >> Joel Becker
> >> Principal Software Developer
> >> Oracle
> >> E-mail: joel.becker at oracle.com
> >> Phone: (650) 506-8127
> >
> > So here I am once again trying to eliminate the use of CDSLs so that
> > I can upgrade past 1.2.x, and I'm finding myself stuck.
> >
> > I have made use of bind mounts for entire directories that were
> > node-specific via CDSL.  However, I have yet to find an alternative
> > for a CDSL that points at a single file.  I've been re-working
> > applications configs and all to reduce depency on CDSL and/or bind
> > mounts, but I've gotten down to only TWO files left which use a
> > CDSL.  And, due to the nature of the application and configuration
> > file I cannot figure a way around the CDSL.
> >
> > Has anyone else gone through this process of getting away from
> > specific file CDSLs?  If so, what did you do?
> >
> > _______________________________________________
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> > Ocfs2-users at oss.oracle.com
> > http://oss.oracle.com/mailman/listinfo/ocfs2-users
>
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Marc Grimme

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