Gluster users - Feb 2010 - Gluster on fast and slow networks

This is an edge case scenario, but one that I am worried about.

Say you have 2 storage nodes as a mirror on a 10G network, and you write 
into a client mount also on the 10G network. Then data will be 
replicated by the client via the 10G network to the 2 servers.
If one server out of sync because it was off line, then any changes 
would be replicated by the client on the first read. which on the 10G 
network is not a problem.

I add more clients that are on a 1G network.
Now if one of the servers is out of sync and the first read is on a 1G 
client then the data would be replicated via the 1G client. This would 
saturate the 1G link on the client and seriously effect its performance.

Is there a work around/solution for this problem?





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Adrian Revill wrote:
> This is an edge case scenario, but one that I am worried about.
>
> Say you have 2 storage nodes as a mirror on a 10G network, and you 
> write into a client mount also on the 10G network. Then data will be 
> replicated by the client via the 10G network to the 2 servers.
> If one server out of sync because it was off line, then any changes 
> would be replicated by the client on the first read. which on the 10G 
> network is not a problem.
>
> I add more clients that are on a 1G network.
> Now if one of the servers is out of sync and the first read is on a 1G 
> client then the data would be replicated via the 1G client. This would 
> saturate the 1G link on the client and seriously effect its performance.
>
> Is there a work around/solution for this problem?
The general idea of having "asynchronous" or delayed replication has 
come up many times on this list.
Such a feature would involve having a "master" and a
"backup" copy of
each file, with the backup copy
lagging behind the master by a few seconds or minutes. This would be 
useful in the case you mentioned
and also if you wanted the backup to be at a different location 
reachable over WAN.

However, we have currently not made any concrete plans about this feature.

Vikas