NFS Performance: Weirder And Weirder

Tim Daneliuk tundra at
Sun Mar 17 03:46:59 UTC 2013

On 03/16/2013 10:15 PM, Mehmet Erol Sanliturk wrote:
> On Sat, Mar 16, 2013 at 6:46 PM, Tim Daneliuk <tundra at <mailto:tundra at>> wrote:
>     On 03/16/2013 05:43 PM, Mehmet Erol Sanliturk wrote:
>         Michael  W. Lucas in Absolute FeeBSD , 2nd Edition ,  ( ISBN : 978-1-59327-151-0 ) ,
>         is suggesting the following ( p. 248 ) :
>         In client ( mount , or , fstab ) , use options ( -o tcp , intr , soft , -w=32768 , -r=32768 )
>         tcp option will request a TCP mount instead of UDP mount , because FreeBSD NFS defaults to running over UDF .
>         This subject may be another check point .
>     Another very good suggestion but ... to no avail.  Thanks for pointing
>     this out.
>     --
>     ------------------------------__------------------------------__----------------
>     Tim Daneliuk tundra at <mailto:tundra at>
>     PGP Key:
> I have read messages once more .
> There is a phrase : Linux Mint 12 machineS ( plural ) .
> In your descriptions , there is no any information about network setup :
> Single client ,
> multiple clients , etc .
> Then , with some assumptions :
> If there is ONLY ONE client , and all of the tests are performed on this ONLY client ,
> problem may be attributed to FreeBSD server or kind of file(s) in different directories :
> One of the is encrypted ( requires decryption ) , another is plain file , etc. .

There is one server - FreeBSD, and one client - LM12.

Both have had their cables replaced with new CAT6 wiring.

Copying the exact same file to each of the NFS mounts exhibits the problem.

Reading from the two NFS mount is fast and as expected, so I do not suspect
network issues.

The two drives used on the server show similar disk performance locally.

The server side exports are identical for both mounts as are the client side

The ONLY difference is that the "fast" NFS mount has server side permissions of
777 whereas the "slow" NFS mount has server side permissions of 775.  Both
are owned by root:wheel.  The contents of each filesystem are owned by a
user in the wheel group.  The one other difference is that all the contents
of the slow mount are in a particular user group, and all the ones in the
fast mount are in the wheel group.   Changing the group ownership of all the
stuff in the slow mount to wheel makes no difference.

The problem appears to be size related on the slow mount.  When I copy,
say, a 100MB file to it, performance is just fine.  When I copy a 1G file,
it's 1/20 the throughput (45MB/sec vs 2MB/sec).

This feels like some kind of buffer starvation but the fact that I can
run at full speed against another mount point leaves me scratching my
head as to just where.  It's almost like there's some kind of halting
going on during the transfer.

Tim Daneliuk     tundra at
PGP Key:

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