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Re: [Linux-cluster] is it possible an active-active NFS server?

Hi Gordan, 

first thanks for your answer and your time 


Whether it will scale is dependant almost exclusively on your access pattern. If you can group your cluster file system accesses so that nodes hardly ever access the same file system subtrees then it will scale reasonably well. If you are going to have nodes randomly accessing the file system paths, then the performance will take a nosedive, and get progressively slower as you add nodes.

This will scale linearly:
Node 1 accessing /my/path/1/whatever
Node 2 accessing /my/path/2/whatever

This will scale inversely (get slower):
Node 1 accessing /my/path
Node 2 accessing /my/path

Cluster file systems are generally slower at random access than standalone file systems, so you are likely to find that having a standalone failover (active-passive) solution is faster than a clustered active-active solution, especially as you add nodes.

interesting, I suposse that active-active will be faster...


So the question really comes down to access patterns. If you are going to have random access to lots of small files (e.g. Maildir), the performance will be poor to start with and get worse as you add nodes unless you can engineer your solution so that access for a particular subtree always hits the same node. OTOH for large file operations, the bandwidth will be more dominant than random access lock acquisition time, so the performance will be OK and scale reasonably as you add nodes.

ok, understood, I´ll try to know the access paterns to get the best solution
Note that this isn't something specific to GFS - pretty much all cluster file systems behave this way.





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