[Samba] Frontend cache VFS

[Nik]

Hi Folks,

I am considering implementing a frontend SAMBA fileserver in front of 
our central fileserver, and am wondering if there are any VFS modules 
that may already do some or all of what I want.

The idea is that the frontend server implements a read-through cache to 
the central fileserver. Client machines would connect to the frontend 
server and request files. The frontend server would either retrieve and 
cache the requested file from the central server, or serve directly from 
its cache. All client updates would be cached on the frontend server 
until committed (periodically) to the central server.

The benefits I'm hoping to realise from this include:

1. The ability to virus-scan updated files on the frontend server before 
committing them to the central server. This allows for a reasonable 
compromise between the performance penalty of on-demand scanning, and 
the security of ensuring all modified files are scanned before being 
committed to the central fileserver.

2. Two levels of file save, so if one of the servers experiences a 
catastrophic disk failure, the data loss is minimised. For example, if 
the cache commits to the central server every hour, then the greatest 
possible data loss is an hour's worth of work. With our current nightly 
backup arrangement, we can potentially lose an entire day's work.

3. A speed-up of our backups, since the frontend server already has a 
record of all modified files which makes the typical scan of the entire 
central server to find those files which have been modified, unnecessary.

If no such VFS currently exists I am considering writing my own, so I 
would be interested in knowing if anyone out there is interested in 
testing and/or deploying such a VFS?

All comments gratefully received.

Cheers!
Nik