[arch-general] NFS close-to-open

[Paul Gideon Dann]

I've been learning about the close-to-open policy of NFS, which causes each 
file to be flushed to the server as it's closed, to ensure consistency across 
clients.  This is a big performance hit when trying to upgrade the system, 
because of the numerous writes to small files.

I know about the "async" export option, obviously, but there is also a "nocto" 
client mount option, which is supposed to disable the close-to-open mechanism 
for that client.  As far as I can tell, this is supposed to stop the client 
from flushing the file when it closes it (as well as not bothering to check 
cache consistency when it opens).  However, this seems to have no effect: the 
client is still flushing the file to the server on close, causing massive 
wait-io.

Does anyone have any idea why "nocto" doesn't have the effect I was hoping it 
would?  The "async" option works as expected, but it's more important to me 
that the client cache is correct, and it just bugs me.

Thanks for any insight,
Paul