Re: Can we setup pNFS with multiple DSs ?

["Goetz, Patrick G" <pgoetz@math.utexas.edu>]

On 6/14/19 5:06 AM, Benjamin Coddington wrote:
> On 13 Jun 2019, at 11:30, Goetz, Patrick G wrote:
> 
>> Every so often I hunt for documentation on how to set up pNFS and can
>> never find anything.  Can someone point me to something that I can use
>> to test this myself?
> 
> The file Documentation/filesystems/nfs/pnfs-scsi-server.txt in the kernel
> source tree is probably the best source of current documentation, if very
> concise:
> 
>      pNFS SCSI layout server user guide
>      ==================================
> 
>      This document describes support for pNFS SCSI layouts in the Linux NFS
>      server.  With pNFS SCSI layouts, the NFS server acts as Metadata 
> Server
>      (MDS) for pNFS, which in addition to handling all the metadata 
> access to the
>      NFS export, also hands out layouts to the clients so that they can 
> directly
>      access the underlying SCSI LUNs that are shared with the client.
> 
>      To use pNFS SCSI layouts with with the Linux NFS server, the 
> exported file
>      system needs to support the pNFS SCSI layouts (currently just XFS), 
> and the
>      file system must sit on a SCSI LUN that is accessible to the 
> clients in
>      addition to the MDS.  As of now the file system needs to sit 
> directly on the
>      exported LUN, striping or concatenation of LUNs on the MDS and 
> clients is
>      not supported yet.
> 
>      On a server built with CONFIG_NFSD_SCSI, the pNFS SCSI volume 
> support is
>      automatically enabled if the file system is exported using the 
> "pnfs" option
>      and the underlying SCSI device support persistent reservations.  On 
> the
>      client make sure the kernel has the CONFIG_PNFS_BLOCK option 
> enabled, and
>      the file system is mounted using the NFSv4.1 protocol version 
> (mount -o
>      vers=4.1).
> 
> Should we have more than this?

I can't tell if you're being facetious, which is a bad sign.  <:)

Yes, most linux admins are probably not going to install the kernel 
source tree looking for documentation.  I personally find that step by 
step howto's (even if they don't match my exact use case) are the best 
way to get an overview of how to use a tool).  Of course it's free open 
source software, so there's no incentive to write documentation, but 
I've been doing this for quite some time and (post the sendmail era), 
there is a pretty clear correlation between the success of an open 
source project and the quality of the documentation that it provides. 
Django (for example) is a pointless web framework, in my opinion, but 
extremely popular because they took the time to write clear documentation.

Anyway, thanks; this at least gives me a starting point for experimentation.



> 
> Ben
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