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November 11, 2008

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Stephen Foskett

Steve,

How does the client communicate the policies to Atmos? I can imagine how with the webby dubby protocols like SOAP, but let's say I'm using NFS and I write a file. How do I say "you know that file I wrote? Replicate it to Shanghai!"?

Thanks,
Stephen

Mike

Hi Steve -

Great post. So how does this per-object policy lookup step affect ingest performance?

Mike

Steve Todd

Stephen,

The client doesn't communicate policies to Atmos. Using your NFS example, the NFS create gets bridged to a local Atmos client, who scrapes out relevant metadata (e.g. NFS client userid), sends it to the MDS, who sends the LSO back to the Atmos client (who caches the LSO). The subsequent NFS writes again bridge to the Atmos client, who examines the cached LSO, and streams content straight to the proper location(s).

Steve

Steve Todd

Mike,

Atmos makes extensive use of policy caching. Initial performance hit on policy lookup, then straight streaming of data to physical location(s).

Steve

Stephen Foskett

Steve,

So there are no policies applied to NFS-written data? Or just generic policies?

Say I write File X via NFS to Atmos. I wouldn't be able to say "send that file to Shanghai"?

Still confused...

Martin G

So in many ways and I know it is more functionally rich than this; if I am accessing file-systems using NFS/CIFS, it kind of works like Acopia. I can set policies on a user/filesystem basis? So if I have a user who I know is a VIP; I could set his files to replicate etc?

I have another question, if user Joe goes to Shanghai and accesses the file; does he access the spun-down version? If so, can the LSO work out that I need that content replicated back?

Steve Todd

Stephen,
As I read your question again I realize I didn't answer it fully.
Once you've written a file via NFS, and it's already been stored (based on policy), any given file can be "moved" somewhere else by creating a new policy specifically for that file. Atmos has a "Job Services" component which will automatically execute the task once the new policy appears.
Steve

Steve Todd

Hey Martin,

Yes, if I know the user is a VIP, I can set his files to replicate.

Your question about "access from Shanghai" is a good one, and begs the question: "how do reads work?". That answer would take a few paragraphs (at least), I think a future post would be more appropriate.

Steve

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  • The opinions expressed here are my personal opinions. Content published here is not read or approved in advance by DELL Technologies and does not necessarily reflect the views and opinions of DELL Technologies nor does it constitute any official communication of DELL Technologies.