Re: expected behaviour for replicated servers

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On Thu, 2017-06-15 at 12:19 +1000, Vincent McIntyre wrote:
> Hello
> 
> I can't see this in the manpages or README.replicated-server,
> perhaps I can provide a patch...
> 
> I have this setup:
> 
> $ grep autofs /etc/nsswitch.conf
> autofs: files nis
> 
> $ cat /etc/auto.master
> /nfs  auto.nfs  -rw,hard,intr,vers=3
> $ ypcat -k auto.nfs
> foo  -ro,hard  boxa,boxb:/export/foo
> 
> 
> Question:
> 
> If boxa has the NFS server running (so autofs ping works)
> but does not export /export/foo,
> what is the expected behaviour?

I haven't looked, so just I'll say what I think should happen.

> 
> boxa and boxb are in different subnets, the client is in
> the same subnet as boxa.

If the network proximity code is working properly boxb probably won't make it to
the list of servers to try because it should look like it's further away.

> 
> What I am seeing is that the automount fails completely
> upon trying boxa. boxb is never tried (no request logged on boxb).
> Looking at the autofs debug log, I can see
> get_nfs_info called for boxa, twice in fact.
> For boxb, only get_supported_ver_and_cost is called,
> after which the daemon tries to mount the share from boxa.

That's likely expected as I'm pretty sure I construct the list of servers that
have the selected characteristics including proximity.

For proximity it will check network address against local interfaces to work
that out so you probably shouldn't see an NFS ping at all as that's used to
establish best response amongst the list of selected servers.

I'd need to have a look at the code.

> 
> 
> What I was hoping to see is that the client also tries boxb
> before giving up.
> 
> I tried fiddling with:
>  the order (boxb,boxa:/export/foo)
>  weights (boxb(3),boxa:/export/foo),
> but none of this made any difference.

If I'm right then boxb won't get onto the list of servers to try so there's
probably not much you can do about it, (again if I am right) possibly it should
change to include the further away servers .... that might not be a straight
forward change ...

Ian
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