[Gluster-devel] Confused on AFR, where does it happen client or server

[Anand Avati]

Brandon,
 who does the copy is decided where the AFR translator is loaded. if you
have AFR loaded on the client side, then the client does the two writes. you
can also have AFR loaded on the server side, and handle server do the
replication. Translators can be loaded anywhere (client or server, anywhere
in the graph). You need to think more on the lines on how you can 'program
glusterfs' rather than how to 'configure glusterfs'.

avati

2008/1/8, Brandon Lamb <brandonlamb at gmail.com>:
>
> I have been reading through old mails for this list and the wiki and i
> am confused on what machine would do the writes for an afr setup.
>
> Say I have two "servers" (192.168.0.10, 192.168.0.11) with configs
>
> -------------
> volume locks
>   type features/posix-locks
>   subvolumes brick
> end-volume
>
> volume brick
>   type storage/posix
>   option directory /mnt/raid/gfs
> end-volume
>
> volume server
>   type protocol/server
>   subvolumes brick
>   option transport-type tcp/server     # For TCP/IP transport
>   option client-volume-filename /etc/glusterfs/glusterfs-client.vol
>   option auth.ip.brick.allow 192.168.0*
>   option auth.ip.brick-ns.allow 192.168.0*
> end-volume
> ------------
>
> and one client (192.168.0.20) with config
>
> ------------
> ### Add client feature and attach to remote subvolume of server1
> volume brick1
>   type protocol/client
>   option transport-type tcp/client  # for TCP/IP transport
>   option remote-host 192.168.0.10 # IP address of the remote brick
>   option remote-subvolume brick     # name of the remote volume
> end-volume
>
> ### Add client feature and attach to remote subvolume of brick1
> volume brick2
>   type protocol/client
>   option transport-type tcp/client  # for TCP/IP transport
>   option remote-host 192.168.0.11 # IP address of the remote brick
>   option remote-subvolume brick     # name of the remote volume
> end-volume
>
> ### Add AFR feature to brick1
> volume afr1
>   type cluster/afr
>   subvolumes brick1 brick2
> end-volume
>
> ### Add IO Threads
> volume iothreads
>   type performance/io-threads
>   option thread-count 4
>   option cache-size 32MB
>   subvolumes afr1
> end-volume
>
> ### Add IO Cache
> volume io-cache
>   type performance/io-cache
>   option cache-size 32MB             # default is 32MB
>   option page-size 1MB               #128KB is default option
>   option priority *.php:3,*.htm:2,*:1 # default is '*:0'
>   option force-revalidate-timeout 2  # default is 1
>   subvolumes iothreads
> end-volume
>
> ### Add writebehind feature
> volume writebehind
>   type performance/write-behind
>   option aggregate-size 1MB
>   option flush-behind on
>   subvolumes io-cache
> end-volume
>
> ### Add readahead feature
> volume readahead
>   type performance/read-ahead
>   option page-size 256kB
>   option page-count 16       # cache per file = (page-count x page-size)
>   subvolumes writebehind
> end-volume
> ------------
>
> So when my client machine copies a 10 megabyte file, does the client
> send this file to server1 and server2, or do the servers figure this
> out?
> Is there server side afr?
>
> My question is along the lines of what happens if i have 10 servers
> (data nodes) and 2 clients, how can i move the load of copying files
> from clients to servers? or is this even possible?
>
> I would think that in a mail cluster setup, i would not want my mail
> servers having the extra load of handling the afr, i would think it
> should send a write to one server and the server handles replicating?
>
> Or am I totally not understanding something?
>
>
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>



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