Re: NFSv4 grace time

[Michael Schwartzkopff <misch@schwartzkopff.org>]

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> On Thu, 21 Jul 2011 15:40:05 +0200
> 
> Michael Schwartzkopff <misch@schwartzkopff.org> wrote:
> > Hi,
> > 
> > setting up a linux NFS server cluster I experience a strange problem
> > during a failover. A client can access a file only after 60 to 90
> > seconds. On the line I see a NFS4ERR_GRACE from the server to the
> > client.
> > 
> > I already set the /proc/fs/nfsd/nfsv4leastime to 10.
> > 
> > Any other idea?
> > 
> > For the tests I have a simple setup:
> > 
> > One host with a simple script that simulates failover:
> > 
> > #!/bin/bash
> > 
> > ip a d 1.2.3.4/24 dev eth0
> > exportfs -u *:/srv/nfs/home
> > exportfs -u *:/srv/nfs
> > /etc/init.d/nfsserver stop
> > #
> > /etc/init.d/nfsserver start
> > exportfs -o fsid=0,rw,crossmnt,no_root_squash *:/srv/nfs
> > exportfs -o fsid=1000,rw,mountpoint,no_root_squash *:/srv/nfs/home
> > ip a a 1.2.3.4/24 dev eth0
> 
> This is normal. The grace period is there to allow clients to reclaim
> their state without other clients racing in and grabbing their locks on
> the new server, etc.

Ok. But this is the same client that cannot its own data.
 
> You can play with /proc/fs/nfsd/nfsv4gracetime too but I'd be very
> leery of setting that too low. It should never be lower than the
> previous leasetime (see the comments on write_gracetime in the kernel).

I did already set this to 10 seconds without success. The client still has to 
wait 60 seconds to access its data.

By the way: Is there a nice way to set this during startup of the nfsserver, 
i.e. a mount option for nfsd?

Greetings,

-- 
Dr. Michael Schwartzkopff
Guardinistr. 63
81375 München

Tel: (0163) 172 50 98
Fax: (089) 620 304 13

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