On Tue, 2012-06-26 at 14:43 +0200, Johannes Schild wrote:
> Hi,
>
> thanks for your answers.
>
> But how do i find out, whether the server is using FILE_SYNC?
You said you were using a NetApp filer. They have an NVRAM cache which
means they will always use FILE_SYNC mode for writes.
> Is there any other mode like "FILE_ASYNC"?
Please see the NFS spec. There are 3 write modes: FILE_SYNC == (data
+metadata committed to disk), DATA_SYNC == (data + file size committed
to disk), UNSTABLE == (data+metadata is cached on the server).
> And if the server is using FILE_SYNC, how does it get LAYOUTCOMMIT?
It doesn't need it. All metadata is already on disk.
> Thanks in advance
>
>
> Johannes
>
>
> -------- Original-Nachricht --------
> > Datum: Mon, 25 Jun 2012 09:46:40 -0400
> > Von: Trond Myklebust <trond.myklebust@xxxxxxxxxx>
> > An: Johannes Schild <JSchild@xxxxxx>
> > CC: linux-nfs@xxxxxxxxxxxxxxx
> > Betreff: Re: LAYOUTCOMMIT/LAYOUTRETURN
>
> > On Mon, 2012-06-25 at 09:43 +0200, Johannes Schild wrote:
> > > Hi Guys,
> > >
> > > i have another question on pNFS. I looked at my Wireshark protocols,
> > while i used the FILE-Layout, and i wondered why i have no
> > LAYOUTCOMMIT/LAYOUTRETURN statements in my protocols.
> > > I transfered one file to my storage server (NETAPP Simulator 8.1 C-Mode)
> > and i only got a LAYOUTGET.
> > >
> > > cat /proc/self/mountstats | grep LAYOUT says:
> > > nfsv4:
> > bm0=0xfafe8fff,bml=0x60fdfffe,acl=0x3,sessions,pnfs=LAYOUT_NFSV4_1_FILES
> > > LAYOUTGET: 1 1 0 216 236 0 1 1
> > > LAYOUTCOMMIT: 0 0 0 0 0 0 0 0
> > > LAYOUTRETURN: 0 0 0 0 0 0 0 0
> >
> > A pNFS client should never send LAYOUTCOMMIT to a server that does
> > FILE_SYNC writes.
> >
> > The Linux pNFS client uses the 'forgetful client' model, so it will
> > never send LAYOUTRETURN on layout recalls either. The only case where we
> > send LAYOUTRETURN is when the file falls out of the inode cache.
> >
> >
> > > Is there any other way to verify that pnfs is used on client site?
> >
> > The most direct way is to look for a TCP connection to the data server
> > using 'netstat -t'.
> >
> > Cheers
> > Trond
> >
>
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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