[Gluster-users] server side afr, workstation unify?

[Keith Freedman]

ok.  I see what you're trying to do.
I belive the afr of the unify in the 2nd another node should be fine.

I'm guessing what you're experiencing is that dream-mirror is empty?

for the AFR brick, I'd add a local read volume as your unify, unless 
you want anothernode2 to read from the mirror, which I think you don't.

Is something mounting afr0?   As I understand it, the afr happens 
when files are accessed through the AFR volume.
So, just defining the volume doesn't accomplish anything.
When you access a file that's mounted on the afr volume (or on a 
volume below the afr volume), the AFR translator, asks both bricks 
for the extended attributes and the file timestamp (and for the 
directory as well).   If they're not the same, then it copies over 
the new one to the mirror(s).  However, if no file request ever 
passes through the AFR translator, then nothing gets replicated.

So, some node has to moun the AFR brick.

your configuration is actually a good one for doing periodic mirroring.
you mount the afr volume, run a find (there are examples in the wiki) 
across the new mount point, thus causing auto-healing of the entire 
volume. then unmount it.
And you have effectively a point in time snapshot.

You then mount it again, run find to auto-heal.

However, if you want "live" replication, then you need the AFR volume 
to be in use and active..

Ideally, you should have ALL the nodes using the AFR config, and 
mounting the AFR volume --- set the unify brick as the read volume.

This way, anytime any node reads data, it reads from the unify and 
anytime any of them write data, it gets written to the mirro via the 
AFR translator.

I hope I understood your intentions clearly.

Keith

At 04:09 PM 8/5/2008, Wolfgang Pauli wrote:
>Hi,
>
>Thanks for you your reply.
>
>Here is the part of my configuration file that might explain better what I am
>trying to do.
>
>-----------
>#glusterfs-server-dream.vol
>
># dream-mirror is the directory where I would like to have a complete copy of
>unify0
>volume dream-mirror
>    type storage/posix
>    option directory /glusterfs-mirror
>end-volume
>
>volume dream
>    type storage/posix
>    option directory /glusterfs
>end-volume
>
># namespace for unify0
>volume dream-ns
>    type storage/posix
>    option directory /glusterfs-ns
>end-volume
>
># another node
>volume neo
>    type protocol/client
>    option transport-type tcp/client
>    option remote-host neo # defined in /etc/hosts
>    option remote-subvolume neo
>end-volume
>
>#another node
>volume echo
>    type protocol/client
>    option transport-type tcp/client
>    option remote-host echo
>    option remote-subvolume echo
>end-volume
>
>volume unify0
>   type cluster/unify
>   option scheduler rr # round robin # going to switch to NUFA
>   option namespace dream-ns
>   subvolumes dream echo neo
>end-volume
>
>volume afr0
>   type cluster/afr
>   subvolumes unify0 dream-mirror
>end-volume
>
>volume server
>    type protocol/server
>    option transport-type tcp/server
>    subvolumes dream dream-ns unify0
>    option auth.ip.dream.allow *
>    option auth.ip.dream-ns.allow *
>    option auth.ip.unify0.allow *
>#   option auth.ip.dream-mirror.allow *
>#   option auth.ip.afr0.allow *
>end-volume
>
>----------
>
># glusterfs-client-dream.vol
>
>volume unify0
>    type protocol/client
>    option transport-type tcp/client
>    option remote-host 127.0.0.1   # IP address of server2
>    option remote-subvolume unify0   # use dream on server2
>end-volume
>
>----------------
>
>the problem with our network is that it is slow (100MBit/s). So it would be
>great if all files (talking about /home/*) would just stay on the
>workstations, unless needed somewhere else. So I would like to do a afr over
>a unify guy, but so far volume dream-mirror remains empty.
>
>Thanks!
>
>Wolfgang
>
>
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