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SubjectRe: [NFS] New version of Linux NFSv3 client is out...
On Tuesday January 25, andrea@suse.de wrote:
> On 25 Jan 2000, Markus Stenberg wrote:
>
> >Nod, and that isn't very good. Although violating NFSv2 protocol _has_ to
> >be done if you want to guarantee any(*) performance, it's still bad idea as
> >default behavior.
>
> I think it make no sense to respect the server-write-sync issue of the
> NFSv2 RFC since on the exporting machine we don't have these garantee
> either (thus it make no sense we don't have them without NFS and we get
> them using NFS). Neither data journaling can help you. Only mounting the
> fs in sync mode with a data-journaling fs would provide to the exported fs
> the semantics the NFSv2 is supposed to provide. So actually I think the
> RFC is way too strict and make no sense to enforce it for the current
> 2.2.x and 2.3.x systems.

There is an important issue that you seem to be missing.
You say
"on the exporting machine we don't have these garantee either"
However, that is not the case. On the exporting machine, you may
choose to use the "fsync" call to get a guarantee. However the NFSv2
protocol does not have any equivalent to the "fsync" call. So if you
export your filesystems with the "async" flag, then when clients call
"fsync", they don't really get the guarantee that they expect.

NFSv3 does have an equivalent of "fsync" - it is spelt "COMMIT".

So with NFSv2, you have two options: safe or fast. I choose "safe".

NeilBrown


>
> It's fine you can enable the strict RFC behaviour it with a param of
> course ;).
>
> Andrea
>
>
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