When does NFSv3 client uses FILE_SYNC?

When does NFSv3 client uses FILE_SYNC?

[Oren D]

Hi all,

Can someone please list for me the conditions under which an NFSv3
client would send FILE_SYNC write requests?

I have the filesystem exported on the server with the sync option
(which is not supposed to prevent the client from writing with
UNSTABLE),
and mounted from the client with the default mount options.

And still i have a user-space application that generates WRITEs with FILE_SYNC!

This is what I know that can make the client write using FILE_SYNC:
- mount -o sync
- open(...,O_SYNC)

Thanks,
Oren.


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Re: When does NFSv3 client uses FILE_SYNC?

[Vincent Roqueta]

Le mercredi 10 Novembre 2004 17:21, vous avez =E9crit=A0:
 Le mercredi 10 Novembre 2004 17:05, Oren D a =E9crit=A0:
 > Hi all,
 >
 > Can someone please list for me the conditions under which an NFSv3
 > client would send FILE_SYNC write requests?
 >
 > I have the filesystem exported on the server with the sync option
 > (which is not supposed to prevent the client from writing with
 > UNSTABLE),
 > and mounted from the client with the default mount options.
 >
 > And still i have a user-space application that generates WRITEs with
 > FILE_SYNC!
 >
 > This is what I know that can make the client write using FILE_SYNC:
 > - mount -o sync
 > - open(...,O_SYNC)

 What kernel is it?
 For a 2.6.x one, if the export's sync option is set all request will be
 synchronised, (even if the file is opened async... )

 (I remember some problems with that... )


 Vincent


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Re: When does NFSv3 client uses FILE_SYNC?

[Oren D]

> Le mercredi 10 Novembre 2004 17:05, Oren D a =E9crit :
>=20
>=20
> > Hi all,
> >
> > Can someone please list for me the conditions under which an NFSv3
> > client would send FILE_SYNC write requests?
> >
> > I have the filesystem exported on the server with the sync option
> > (which is not supposed to prevent the client from writing with
> > UNSTABLE),
> > and mounted from the client with the default mount options.
> >
> > And still i have a user-space application that generates WRITEs with
> > FILE_SYNC!
> >
> > This is what I know that can make the client write using FILE_SYNC:
> > - mount -o sync
> > - open(...,O_SYNC)
>=20
> What kernel is it?
> For a 2.6.x one, if the export's sync option is set all request will be
> synchronised, (even if the file is opened async... )
>=20
> (I remember some problems with that... )
>=20
>=20
> Vincent
>=20

Kernels are 2.4 (RH9) both client and server.
I read that the sync export option does not prevent the client (in NFS
v3) from working async.
And i see it for a fact when using simple dd or cp commands. It's only
that specific application generating FILE_SYNC writes on the same
mounted filesystem. It has to be something controlled by a userspace
application. I checked with the authors of the application, and they
say their not using O_SYNC, that's why i'm looking for other options.

Regards,
Oren.


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