[Gluster-users] Unify and single namespace

[a s p a s i a]

Hello all,

I have reviewed the docs, instructions, etc... but I do not seem to
get the "picture" of how the single metadata namespace would fit into,
for instance a 4-brick architecture ... of Gluster.

1.  The FAQ discusses that when the Unify Translator is enabled,
metadata is stored on the namespace brick.

 Metadata Storage - When using striping (unify), how/where is the
metadata kept? The metadata is stored on the namespace brick.

What does this mean?  We would need to dedicate a separate metadata
server (in addition to my storage nodes)?  But does not seem so, as
the installation binaries seem to only come in "server" and "client"
form.

2.  I further read the Unify Translator doc -
http://www.gluster.org/docs/index.php/Understanding_Unify_Translator

and seems like the following states that the "namespace-child" needs
to be another volume defined in the spec, configured like another
server brick, but its content is used to manage namespace. QUESTION -
is this a dedicated server?


•	LINE 5: "option namespace namespace-child"
The option specifies that namespace-child should be used as a place
where the whole filesystem's namespace (ie, directory/file tree
structure) is maintained. Here 'namespace-child' needs to be another
volume which is already defined in the spec.
'namespace-child' is configured like another server brick, except that
it's content is used to manage namespace. It should not be listed
along with the other subvolumes.
•	LINE 6: "subvolumes child1 child2 child3 child4"
Here 'subvolumes' is an identifier for parser to tell that following
volumes are the 'children' nodes for current volume. 'subvolumes'
takes one or more volume names as argument. Here child1, child2,
child3, child4 are also named as storage nodes as these are the nodes
where actual data is storaged.

======

Could someone point me to a site that potentially diagrams a summary
of a simple Gluster with Unify and AFR installed?

I found this site:
http://ftp.zresearch.com/pub/gluster/glusterfs/talks/Z/GlusterFS.pdf -
page 5 - shows the Unify stack in the client, but I still am unable to
conceive where the metadata - single namespace information - is
stored?

I apologize if my question is quite naive, but I'm a bit confused.

thanks in advanced,

aspasia.