Subject: Re: [nfsv4] slides

From: "Mkrtchyan, Tigran" <[email-masked]>
Date: Sat, 16 May 2020 23:05:49 +0200 (CEST)

Hi Dave,

Unfortunately I was unable to connect on April 29 ...
I have a comment about directory delegation.

For us (the crazy scientist) the directory delegation
*had* a big potential. First of all, some of our workflows
produce literally millions of files in a single directory,
something like generating a HD movie with one file per frame.
Second, as every scientist wants to be the first to make
the new discovery, people ran scripts that do `ls` in a loop
and spawn a processing job as soon as new a data is detected.
This makes GETATTR and REDDIR to most demanded operations.

To keep our users happy, we put a significant effort to make
directory listing as fast/cheap as possible and have introduced
so called 'storage events' - a mechanism where storage system can
perform user defined actions triggered on certain events. The AWS
Lambda is probably the closest commercial alternative.

There are two reasons why we didn't go for directory delegation:

  - my poor skills as kernel developer
  - the time it takes upstream kernel to
    land on our production nodes (we still run RHEL6)

If interest is still there, I am not the one who can do the kernel work,
but I am ready to help with testing and provide a server implementation.

Indeed, the question is should NFS go in that direction. We have tamed
our local users, but there are many others around. Do they have similar
use-case? Do we know and understand their needs?

Best Regards,
   Tigran.

----- Original Message -----
> From: "Dave Noveck" <[email-masked]>
> To: "NFSv4" <[email-masked]>
> Sent: Wednesday, April 29, 2020 6:59:44 PM
> Subject: [nfsv4] slides

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