[CentOS] NFS performance - default rsize

[Alex Still]

[...]

>> On some servers this behavior returned despite rsize being set to 32k,
>> I had to set it to 8k to get reasonnable throughput. So there's
>> definitly something fishy going on. This has been reported on over 20
>> machines, so I don't think it's faulty hardware we're seeing.
>>
>> Any thoughts, ideas on how to debug this ?
>
> Can you explain the network environment and the connectivity between the client and server some more.

Clients are blade servers. The blade chassis have integrated cisco
switches, which are plugged to a cisco 6509. The NFS server is on
another site 40km away, directly connected to another 6509.  These
datacenters are linked via DWDM.
Latency between a client and the NFS server is about half a
millisecond. Jumbo frames are enabled.

Blades have 1 Gb link
The NFS server has multiple 1Gb links, used for different shares
Neither are close to full utilization, maybe 100Mb/s of traffic and 20
000 paquets/s at the server end


Alex