Re: LAYOUT4_NFSV4_1_FILES supported? Re: Can the PNFS blocklayout of the Linux nfsd server be used in a production environment?

["Chuck Lever" <cel@kernel.org>]

On Fri, Nov 28, 2025, at 6:16 PM, Rick Macklem wrote:
> On Fri, Nov 28, 2025 at 8:24 AM Chuck Lever <cel@kernel.org> wrote:
>>
>>
>>
>> On Fri, Nov 28, 2025, at 3:57 AM, Sebastian Feld wrote:
>> > On Thu, Nov 27, 2025 at 5:41 PM Chuck Lever <cel@kernel.org> wrote:
>> >>
>> >> On Wed, Nov 26, 2025, at 9:14 PM, Zhou Jifeng wrote:
>> >> > Hello everyone, I learned through ChatGPT that the PNFS blocklayout of Linux
>> >> > nfsd cannot be used for production environment deployment. However, I saw
>> >> > a technical sharing conference video on YouTube titled "SNIA SDC 2024 - The
>> >> > Linux NFS Server in 2024" where it was mentioned that the PNFS blocklayout
>> >> > of nfsd has been fully maintained, which is contrary to the result given by
>> >> > ChatGPT.
>> >> >
>> >> > My question is: Can the PNFS blocklayout of nfsd be used for
>> >> > production environment deployment? If yes, from which kernel version can it
>> >> > be used in the production environment?
>> >>
>> >> Responding as the presenter of the SNIA SDC talk:
>> >>
>> >> There's a difference between "maintained" and "can be deployed in a
>> >> production environment". "Maintained" means there are developers
>> >> who are active and can help with bugs and new features. "Production
>> >> ready" means you can trust it with significant workloads.
>> >>
>> >> The pNFS block layout type has several subtypes. Pure block, iSCSI,
>> >> SCSI, and NVMe.
>> >
>> > What about the LAYOUT4_NFSV4_1_FILES layout type? Is that still supported?
>>
>> Above, we're talking about the Linux NFS server... IIRC NFSD never
>> supported the NFSv4.1 file layout type. It has a simple experimental
>> implementation of the flexfile layout type (the MDS and DS are the
>> same server).
> Once upon a time Benny Halevy had a single server (in the Linux
> kernel) that did file layout. (I remember because that is what I used
> for testing the FreeBSD client side.) It even knew how to do striping.
>
> However, it was a "single server" (MDS and DS in the same Linux kernel nfsd),
> so it was only useful for testing purposes.
>
> I have no idea if it is still around somewhere, but unless someone wants
> to do a lot of work on it, it is definitely not useful for production sites.

I am going to guess that was Dan Muntz's prototype. AFAIK that was
never merged upstream, but remains available in archive form at
git.linux-nfs.org.

NFSD continues to implement only the block-related layout types,
plus flexfile (in toy form).


-- 
Chuck Lever