StorNext File System Tuning
The Distributed LAN (Disk Proxy) Networks
StorNext File System Tuning Guide 20
background for improved performance. The default setting is optimal in
most scenarios.
The auto_dma_read_length and auto_dma_write_length settings determine
the minimum transfer size where direct DMA I/O is performed instead
of using the buffer cache for well-formed I/O. These settings can be
useful when performance degradation is observed for small DMA I/O
sizes compared to buffer cache.
For example, if buffer cache I/O throughput is 200 MB/sec but 512K
DMA I/O size observes only 100MB/sec, it would be useful to determine
which DMA I/O size matches the buffer cache performance and adjust
auto_dma_read_length and auto_dma_write_length accordingly. The lmdd
utility is handy here.
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 0The 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 Configuration0SNFS 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