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[nfsv4] Re: Erasure coding vs delegations

Thomas Haynes <loghyr@gmail.com> Thu, 05 December 2024 16:11 UTC

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From: Thomas Haynes <loghyr@gmail.com>
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Subject: [nfsv4] Re: Erasure coding vs delegations
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> On Dec 4, 2024, at 1:04 PM, Rick Macklem <rick.macklem@gmail.com> wrote:
> 
> Hi,
> 
> A simple comment w.r.t. Tom's talk to-day on Erasure coding.
> 
> I'll admit I have not read your draft, but I was wondering if
> you have looked at the relationship between your erasure encoding
> work and delegations?
> 
> In particular, a write delegation issued by the MDS to a client
> would ensure exclusive writing and, as such, issuing write
> delegations "generously" might reduce your write contention
> problem?
> 
> Just a thought, rick


Hi Rick, 

The problem is that we want to share the file for multiple writers. :-)

In general the problem is that the applications are writing non-aligned block data.

Client 1 is accessing 0 - 13k and client 2 is accessing 13k -> 20k. Each data block except 12-16k can be written with no expectation of collision. That edge block is different.

Thanks.
Tom

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