More on DFS Replication Limits

A customer recently asked us to clarify the 1-TB DFS Replication limit described in an earlier post. Shobana Balakrishnan, our DFS Replication program manager, explains:

There are no architectural underpinnings of the 1TB limit – it is merely what we tested.  The Jet limits are much larger.  The theoretical limit comes from the number of files under a volume scope due to Jet limits and of course recovery times.  Theoretically the Jet DB can grow as large as 32 TB and assume ¼ used for ID records -> 8TB. Assuming an ID record is 1KB worst case, that is 8*10^9 files on the volume.

On a practical note, we have tested over 50 million files taking approx 1 TB of disk space. The database in this case was approx 20 GB.

I should also clarify bullet (5): A replication group can contain up to 256 members.

This is actually not a global replication group limit. A replication group can be arbitrarily large scaling to several thousands of members.  Each member must however only be connected to at most 256 partners – and actually this translates to bullet (3) where each server should have at most 128 partners (replicating in-and out).