Bad performance of 7.0 nfs client with Solaris nfs server

Chuck Swiger cswiger at
Wed Feb 20 21:30:15 UTC 2008

On Feb 20, 2008, at 1:01 PM, Alfred Perlstein wrote:
>> Take a look at the level of packet fragmentation you are  
>> encountering;
>> yes, this is expected and things will work but there is extra latency
>> added when the IP stack has to reassemble packets before the data can
>> be delivered.  Try setting the NFS rsize/wsize to 1024 or perhaps  
>> 1400
>> and see whether that improves performance.
>> Or, if your switch and NICs support it, see whether you can get Gb
>> Ethernet jumbo frames working so that you don't have to fragment for
>> 2K or 4K data packets....
> TCP mounts do not have this problem.  You can safely use
> 32k or higher sizes with TCP without fragmentation.

Oh, sure.  But there is a bit more overhead with TCP transport than  
UDP-- for local (switched) networks, UDP generally seems to be a  
win...TCP seems to be a better choice over a VPN or some similar kind  
of WAN.


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