Effect of NFS4ERR_DELAY on the client

Effect of NFS4ERR_DELAY on the client

[DENIEL Philippe]

Hi,

I have a question about NFS4ERR_DELAY. What is the behavior of the 
client when such an error is returned. Does it retry ? If yes, how many 
times and with what kind of interval between each retry ?
Is the behavior similar to what the NFSv3 client when receiving 
NFS3ERR_JUKEBOX ?
My purpose is to run NFSv4.x on top of a namespace whose entries can be 
migrated : opening a file may require staging it (in this case 
NFS4ERR_DELAY and NFS3ERR_JUKEBOX will be returned)

     Philippe

Re: Effect of NFS4ERR_DELAY on the client

[J. Bruce Fields]

On Thu, Oct 14, 2010 at 01:48:29PM +0200, DENIEL Philippe wrote:
> Hi,
> 
> I have a question about NFS4ERR_DELAY. What is the behavior of the
> client when such an error is returned. Does it retry ? If yes, how
> many times and with what kind of interval between each retry ?
> Is the behavior similar to what the NFSv3 client when receiving
> NFS3ERR_JUKEBOX ?
> My purpose is to run NFSv4.x on top of a namespace whose entries can
> be migrated : opening a file may require staging it (in this case
> NFS4ERR_DELAY and NFS3ERR_JUKEBOX will be returned)

For the linux client, see fs/nfs/nfs4proc.c:nfs4_delay() and
nfs4_handle_exception():  looks like it starts with NFS4_POLL_RETRY_MIN
== .1 second, and doubles it each time up to NFS4_POLL_RETRY_MAX == 15
seconds.

--b.