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[ts-7000] Re: strange buffering of nfs file

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Subject: [ts-7000] Re: strange buffering of nfs file
From: "j.chitte" <>
Date: Sat, 13 Jun 2009 08:32:33 -0000
--- In  "j.chitte" <> wrote:
>
> --- In  "charliem_1216" <charliem_1216@> wrote:
> >
> > --- In  "j.chitte" <j.chitte@> wrote:
> > >
> > > Hi,
> > > 
> > > I'm booting to an nfs image that contains a script. The first line is:
> > > 
> > > #! /usr/bin/mawk -f
> > > 
> > > I want to edit this use awk but every time I change and save it, it 
> > > springs back to reading mawk.
> > > 
> > > I have editted it with nano on the host and with vi via minicom on the 
> > > running SBC but I can't get the change to stick.
> > > 
> > > In fact it's when I reopen with vi that it gets set back. 
> > > 
> > > If I change it with vi and :wq , I can see it saves correctly by looking 
> > > at the file on the host. But if I reopen with vi it is set back to mawk.
> > > 
> > > Can anyone suggest what is happening?
> > 
> > Be sure to set the sync option in your exportfs lines.
> > 
> > There is a long history here; see nfs.sourceforge.net and the howto 
> > (http://nfs.sourceforge.net/nfs-howto/ar01s05.html#sync_versus_async) 
> > specifically.
> > 
> > Basically, if async is used by the server, the server has permission to 
> > ignore client O_SYNC requests.
> > 
> > regards, ........ Charlie
> > > 
> > > TIA
> > >
> >
> Thanks, I did not think I knew that but apparently I did.
> 
> bash-4.0#/usr/sbin/exportfs -v
> /mnt/nfs        arm.localdomain(rw,wdelay,no_root_squash,no_subtree_check)
> /mnt/nfs        linbox.localdomain(rw,wdelay,no_root_squash)
> 
> The absence of async indicating it is mounted sync.
> 
> /mnt/nfs is a bind mount to where I actually work on the image and it it is 
> what I refer to in my redboot exec command.
> 
> What is even odder is that I managed to add a comment in line 2 of the file 
> that stuck but mawk keeps coming back in line 1.
> 
> :?
>

Having rebooted both systems overnight I now see awk as I require.

I have not pinned down exactly what sequence produces the error but something 
is clearly wrong with nfs sync.

It seems that nfs is not reliable (I've seen several such comments in the past) 
and should be used with circumspection.

Editing files on the nfs mounted system seems to be a bad idea. An nfs restart 
and sbc reboot is the only time I can believe what I see.

:(




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