[Gluster-devel] volume stanzas for non-existent directories in server volume specification

[Brandon Lamb]

On Thu, May 1, 2008 at 1:49 PM, John Marshall <John.Marshall at ec.gc.ca> wrote:
>
> Brandon Lamb wrote:
> > Replies are inline, hopefully im right here.... ;-)
> >
> > <spec example snipped>
> >
> >
> >
> > > Note: it is assumed that host-a:/data/a, host-b:/data/b,
> > > host-ns:/data/ns exist.
> > >
> > > Q. Does gluster have a problem with server spec volumes which do
> > > not exist on a given host?
> > >
> > >
> >
> > I believe you are asking "what happens when you export a non-existant
> > directory as a volume?". There should be an error in the logs correct?
> >
> >
> > > From the "Aggregating Three Storage
> > > Servers with Unify" example is does not seem like it would, since
> > > the namespace volume is _not_ on all nodes.
> > >
> > >
> >
> > Right, when creating your client volume spec you define which server
> > to get the ns volume from. See below. Line 4 defines the remote host
> > to get the remote ns sub volume. Line 5 specifies the name of the ns
> > subvoluem from the server spec file. However if all of your servers
> > are using the same server volume spec file that you included in your
> > original post, then to be correct they *should* all have a ns
> > directory in order to not give an error. But on your clients, it is
> > only going to use the ns directory on the server that you specify in
> > the volume definition (line 1).
> >
> > 1 volume remote-ns
> > 2       type protocol/client
> > 3       option transport-type tcp/client
> > 4       option remote-host host-ns
> > 5       option remote-subvolume ns
> > 6 end-volume
> >
> >
> Right. So, in cases in which a namespace volume is specified, I gather
> that I should expect there to be an error logged on all server hosts except
> the one exporting the namespace. And, that such errors are _not_ fatal.
>
> To expand, the example server volume specs seem to be minimalistic by
> specifying:
> -----
> volume brick
>   type storage/posix
>   option directory /data/export
> end-volume
> -----
> This assumes uniformity of the "exported" filesyetem (i.e., /data/export)
> and allows a common "volume brick" for the stanza.
>
> My question comes from wanting to export multiple, differently named,
> directories from different hosts (assume 1 dir/host). Must I create a
> separate server volume spec for each host, or can I simply put all the
> information into one spec file and ignore the errors?
>
>
>
> Thanks,
> John

If the directory names are different on all of your servers, then yes
they will all have different spec files. Using a single spec file that
is identical on all servers would assume that the volume you are
exporting has the same exact directory name on all servers.

So in your case, your server spec files will be *mostly* identical
except for the "option directory <DIRECTORY>" line which will point to
the volume directory for the given server.