Re: [Gluster-devel] GlusterFS Example

[Nathan Allen Stratton]

On Tue, 31 Jul 2007, Matt Paine wrote:

> Absolutly, except its there is a bit more work to do. AFR works by
> starting at the first brick and any replicating goes to the second,
> third etc as described above. But these are normal gluster bricks, so
> there is nothing stopping you from creating an AFR for the first brick,
> and AFR for the second, and just a posix brick for the rest (if thats
> what you want of course). Let me try to explain.....

Wow, you should put this on the wiki, this is a very clear example. I can
see how this can work, but does it need to be that hard to setup? How hard
would it be to add functionality to AFR where you only need to specify the
number of copies you want and the scheduler takes care of the rest?

> Server one has one brick: S1
> Server two has one brick: S2
> Server three has one brick: S3
> Server four has one brick: S4
> Server five has one brick: S5
>
> Client unifies S1 and S2 (call him U1)
> Client unifies S3 and S4 (call him U2)
> Client then AFR's together U1 and U2 and S5
>
> In this example, if I save a file and its *:3, it will appear....
> * on U1 (either S1 or S2 depending on scheduler)
> * on U2 (either S3 or S4 depending on sched.)
> * on S5
>
> If I save a file as only *:1, it will appear only on U1 (either S1 or S2
> depending on scheduler).
>
> Ad nausium.
>
>
> Of coures there is nothing stopping you from unifying three bricks, or
> even unifying an afr to afr.
>
>
> i.e. (might need a mono spaced font to see correctly...)

I use Pine (old text based mail reader) so it looks great!

>                          A5
>              +-----------------------+
>              |                       |
>              U1                      U2
>       +-------------+           +---------+
>       |             |           |         |
>       A1            A2          A3        A4
>   +---+---+   +---+---+---+   +---+   +---+---+
>   |   |   |   |   |   |   |   |   |   |   |   |
> S01 S02 S03 S04 S05 S06 S07 S08 S09 S10 S11 S12
>
>
> Where Sxx = Server bricks
>         Ax = AFR brick
>         Ux = Unify brick
>
>
>
> So in this configuration (which you have already worked out i'm sure)
> that if you save something *:2, then it will appear in both U1 and U2,
> which means (depending on the spec from a[1-4], assume *:2) it will
> appear in either A1 or A2 (because of the unify), AND it will also
> appear in either A3 or A4. etc etc etc.....
>
> I think i've laboured the point far enough :)

Thanks, it was great!

> Which version of glusterfs are you using? tla, pre ?
>
> (that issue has been fixed for a little while now, so if your using pre6
> you shoulnd't have come across it)

Yep, that was it, I was using 1.2, latest 1.3 fixes the problme.


><>
Nathan Stratton                         CTO, Voila IP Communications
nathan at robotics.net                  nathan at voilaip.com
http://www.robotics.net                 http://www.voilaip.com