NAS is much more scalable than traditional file servers with DAS storage, but
NAS does have some scalability issues. Eventually, the applications’ required
capacity will exceed the capacity of the NAS device. When this happens, there
are two basic ways to solve the scaling issue:
Forklift upgrade of the NAS system to a larger one. This is costly not
only in terms of capital costs, but also in terms of operational costs,
because the data must be migrated to the new system. This can be a
complicated process, especially when there is a strong need to minimize
downtime.
Create a NAS cluster and proxy the IP addresses of the NAS servers so
that the cluster resources look like they belong to a single NAS device
on the network.