User's Manual

StorNext File System Tuning
The Distributed LAN (Disk Proxy) Networks
20 StorNext File System Tuning Guide
The dircachesize option sets the size of the directory information cache
on the client. This cache can dramatically improve the speed of readdir
operations by reducing metadata network message traffic between the
SNFS client and FSM. Increasing this value improves performance in
scenarios where very large directories are not observing the benefit of
the client directory cache.
SNFS External API The SNFS External API might be useful in some scenarios because it
offers programmatic use of special SNFS performance capabilities such
as affinities, preallocation, and quality of service. For more information,
see the
Quality of Service chapter of the StorNext User’s Guide API Guide.
The Distributed LAN (Disk Proxy) Networks
As with any client/server protocol, SNFS Distributed LAN performance is
subject to the limitations of the underlying network. Therefore, it is
strongly recommended that you use Gigabit (1000BaseT) for Distributed
LAN traffic. Neither TCP offload nor jumbo frames are required.
Hardware
Configuration
SNFS Distributed LAN can easily fill several Gigabit Ethernets with data,
so take special care when selecting and configuring the switches used to
interconnect SNFS Distributed LAN clients and servers. Ensure that your
network switches have enough internal bandwidth to handle all of the
anticipated traffic between all Distributed LAN clients and servers
connected to them.
A network switch that is dropping packets will cause TCP
retransmissions. This can be easily observed on both Linux and Windows
platforms by using the netstat -s command while Distributed LAN is in
progress. Reducing the TCP window size used by Distributed LAN might
also help with an oversubscribed network switch. The Windows client
Distributed LAN tab and the Linux dpserver file contain the tuning
parameter for the TCP window size. Note that Distributed LAN server
remounts are required after changing this parameter.