[Gluster-devel] df -kh not reporting correct value

[Amar S. Tumballi]

Daniel,
 Thank you very much for explaining '-n' option properly here. I added the
same explaination in 'http://www.gluster.org/docs/index.php/Man_glusterfs'.

 Hope it helps everyone.

Regards,
Amar

On 7/12/07, Daniel van Ham Colchete <daniel.colchete at gmail.com> wrote:
>
> On 7/11/07, DeeDee Park <deedee6905 at hotmail.com> wrote:
> >
> > Thanks, been very helpful. I'll look into the -n option to check out
> each
> > brick.
> > i worked with a deveoper before, and they said my config was all good
> when
> > i was having problems. They probably have like 3 copies of my configs.
> >
> > assume it is something like
> > # glusterfs [all my other options] -n <brickname>
> > and it will check out only that one brick.
> >
> > Can then i add 2 bricks eg
> > -n brick1 -n brick2
> >
> > to see the cumulative effects.
> >
>
> You can only specify one '-n' option. This will be the brick that
> GlusterFS
> client will mount. The default is to mount the last brick at the volume
> spec
> file.
>
> Imagine the following case:
>
> volume client1
>         type protocol/client
>         option transport-type tcp/client
>         option remote-host 127.0.0.1
>         option remote-subvolume brick1
> end-volume
>
> volume client2
>         type protocol/client
>         option transport-type tcp/client
>         option remote-host 127.0.0.1
>         option remote-subvolume brick2
> end-volume
>
> volume afr
>         type cluster/afr
>         subvolumes client1 client2
>         option replicate *:2
>         option self-heal on
> end-volume
>
> volume writebehind
>         type performance/write-behind
>         subvolumes afr
> end-volume
>
>
>
> If you 'glusterfs (all options) -n client1 /mnt/gluster' you will mount
> only
> the client1 brick there. If you 'glusterfs (all options) -n client2
> /mnt/gluster' you will mount only the client2 brick there. Them you can
> 'df
> -h' on each and see who Gluster is seeing them before AFR.
>
> Now, if you 'glusterfs (all options) -n afr /mnt/gluster' you will mount
> both bricks, but now following the AFR rules, and without the writebehind
> translator active.  Here you can do some benchmarking to measure, latter,
> how good  writebehind is for you.
>
> If you only 'glusterfs (all options but -n) /mnt/gluster)', the last
> (writebehind) brick will be mounted. So now you access all the chain from
> the beginning to the end.
>
> It makes very little sense to 'glusterfs -n brick1 -n brick2' because
> GlusterFS does not know how to work with two translators at the same time.
> How would it know if it would have to distribute files between the bricks
> or
> to replicate them?
>
> GlusterFS can only connect to one brick. This brick, depending on it's
> translator logic, can connect to one or more bricks and do whatever it
> wants
> with them, but Gluster has to have a unique starting point always.
>
> This translator design is very, very, very clever. I can't wait to see the
> possibilities from the compression translator. Depending on how you mount
> the chain you can:
> 1 - compress and uncompress the files at the servers, removing the
> compression burden from the clients, or
> 2 - compress before protocol, uncompress just after, writing the files at
> plain but making better use of the interconnects, or
> 3 - have the clients compressing and uncompressing everything, the server
> will be totally unaware of it, and making a more scalable setup.
>
> The current documentation on what translator are, how you should think of
> them, and how powerful is this organization is a little thin at the wiki,
> but as soon as you understand it you will also love it (as I do).
>
> Best regards,
> Daniel Colchete
> _______________________________________________
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>



-- 
Amar Tumballi
http://amar.80x25.org
[bulde on #gluster/irc.gnu.org]