Best Practice for backing up VNX (multi-protocol)

Hi,

I am redoing my backup strategy and am looking for comments on what works for other folks.  I have 24TB currently and will either grow to 36TB or over 100TB in a 3 years (depends on a decision made several levels above me).  Most of my file systems are multiple protocol so I have been using NDMP for backups as it is suppose to restore permissions for both cifs and nfs.  I use NDMP with Netvault software to a Data Domain located offsite (not directly attached to the VNX).  Right now I have a 1GB link in the pathway, but after this upgrade I will have 10GB links between the VNX -> Netvault server -> Data Domain.  It currently takes me around 48 hours for a full backup.

My questions are:

1. Will NDMP scale to 100 or even 200TB?  Do other folks use NDMP for 200TB backups?  I think I will be ok in my backup window with the faster link, but are their any limits on the number of files in a file system (my largest now is around 4 million files and that is the one that will grow if I end up with the larger amount of disk space).

2. The other option I am looking are continuous incremental backups (e.g. Commvault or TiBS).  The advantage is that I am only backing up the changes.  The issue they have is that they backup via a cifs or nfs share so they only see the permissions of the share protocol.  So, for example, if I backup via nfs and do a restore, the restored files will not have the correct cifs permissions.  The vendors are asking if I have checked into emcgetsd or getfacl as a way to get and save the permissions.  Has anyone done something like this before?

Thanks in advance for your comments.

cheers,

ski