Re: [Gluster-devel] unify translator & namespace

[Amar S. Tumballi]

This mail may be bit detailed. But I hope you all had gone through "
http://www.gluster.org/docs/index.php/Understanding_Unify_Translator"; for a
brief info about the Unify translator.

I am sorry that I didn't update the page with much info about Namespace
brick, and its requirement.

If you just think generally (not going very deep technically), you may
observe the complexity of cluster filesystems. With our goal of not having
metadata for filesystem, we had to think of someways to handle the unified
view of namespace.

We could have given a unified view after doing parallel readdir()s on
servers. But it will surely hit the performance, but not just that, during
file creation, if two nodes try to create files with same names, without a
centralized server which can maintain namespace locks, it would lead to
filesystem corruption. Hence we came up with a namespace design, which will
not contain any critical data, and also it can rebuild from scratch if you
choose to use different new namespace after a while.
So, the namespace brick is required for giving a high performance, and
proper functionality for the cluster file system. Till now we haven't hit
the issues with performance or scalability with having just one namespace
(other than when namespace brick goes down, and its not afr'd). But as we
know that its going to be an issue going further, we have decided to bring
in a distributed namespace from 1.4.x versions.

About your question, whether its mandatory to use namespace, YES it is. If
you don't give this option, you will not be able to mount GlusterFS
filesystem. (As I said earlier its going to change from 1.4.x releases).

Regards,


On Mon, Mar 17, 2008 at 1:54 PM, <address@hidden> wrote:

> Hello !
>
> can someone explain if or why i need a namespace with unify translator ?
>
> is it mandatory or not ?
>
> if not, what`s the disadvantage of not using namespace ?
>
> thanks you!
> regards
> roland
>
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-- 
Amar Tumballi
Gluster/GlusterFS Hacker
[bulde on #gluster/irc.gnu.org]
http://www.zresearch.com - Commoditizing Supercomputing and Superstorage!