What is the internal technical difference between file-based replication and volume-based replication, if both are host-based? What are the benefits and weaknesses of each approach?
At a high level, the main difference would be granularity. Volume-level replication is not concerned with which files have changed. If the volume replication software is capable of replicating only the blocks of data that have changed since the last replication (as opposed to replicating the entire volume), this can significantly reduce the amount of data to be transferred. On the down side, if you only want specific directories or files replicated, you will have to do some upfront work and categorize data per volume.
File-based replication does offer the ability to replicate only specific files. However, if as little as one bit of data has changed on a very large file, the entire file is considered as having changed and will be replicated with most solutions. This can significantly impact replication performance. File-level replication can also include a certain amount of file system overhead, which would further impact performance.
This was first published in February 2005