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Re: [Samba] Am I nuts to attempt a VFS local cache module?

Thanks Jeremy.  I'm going to look at the links you provided and try to do some initial coding, I'm thinking a couple of weeks.  It's not that I think I can produce the thing in a couple of weeks, but I'm the type of programmer who doesn't understand anything until I've written some code on it.


On 4/10/2019 1:50 PM, Jeremy Allison wrote:
On Wed, Apr 10, 2019 at 01:26:59PM -0700, Mark Winslow via samba wrote:
Sorry if this isn't the right place to ask this question.

I'm thinking of writing a module that intercepts Samba requests to keep only
a subset of a file store on a local server with the rest being stored on a
cloud.  It would be an open source module similar to these products:



I'm thinking that I would have to do the following.

1. Keep my own directory lists, probably in Mongodb
2. Intercept File Open,Dir,and Stat requests from Samba
3. When a request to open is received for a file that doesn't exist locally,
create a thread to retrieve the file from the cloud, blocking the request
until the file is retrieved.
4. Have a background process that archives files to the cloud when necessary
5. Have a background process that retrieves files from the cloud when the
local store needs to be rebuilt.

If Samba does any file access operations outside of interceptable VFS
requests, then I guess I'm out of luck.
No it doesn't. *Everything* goes through the VFS for
just this reason. You're in luck :-).

The reasons I'm interested in doing this are:

1. Won't have to incessantly worry about disk size on  servers
2. Can rebuild servers seemlessly from cloud when local server is

Is this idea wrong?
No, it's a great idea ! See here:


for a possible design (from 2015 no less :-).

Has it already been done?  Is there a better
Had the design, no time to write it. I'm happy
to help with anything you want to discuss :-).

Loughborough University in the UK wrote this code
but never released it back to the community (I
asked, they ignored me :-( ).


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