We have taken over an application which had "pretend" failover. Essentially it had two servers with automatic failover between the two. However they both relied on another server for providing the data storage via NFS all the way down to the MySQL server. Interesting how one can manage to provide no real failover with 3 servers. Obviously we want to fix this and actually a number of servers have already been bought. So now we have moved the MySQL server with a cold standby on separate machines. We also have 3 frontend servers which we want to load balance. We will probably use memcache to manage the sessions, as we are not so worried about a lost session when a crash occurs. But now comes the problem: There are a lot of places where administrators and end users can upload files, which end up in the file system. Now how do we replicate those files across all the nodes?
The temporary approach we will be taking will be using NFS with rsync. One …
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