Quantum 6-01376-05 User Manual

  StorNext File System Tuning

The Metadata Controller System

StorNext File System Tuning Guide

12

severely consumes metadata space in cases where the file-to-directory 

ratio is less than 100 to 1. However, startup and failover time can be 

minimized by increasing FsBlockSize. This is very important for multi-

terabyte file systems, and especially when the metadata servers have 

slow CPU clock speed (such as Sparc and Mips). A good rule of thumb is 

to use 16K unless other requirements such as directory ratio dictate 

otherwise. Note that this setting is not adjustable after initial file system 

creation, so it is very important to give it careful consideration during 

initial configuration.
Example: 

FsBlockSize             16K 

0

The optimal settings are in the range between 16M and 64M. Avoid 

values greater than 64M due to potentially severe impacts on startup and 

failover times. Values at the higher end of the 16M-64M range may 

improve performance of metadata operations in some cases, although at 

the cost of slower startup and failover time. A good rule of thumb is to 

use 16M unless another requirement dictates differently. This setting is 

adjustable using the 

 utility. For more information, see the 

 man page.

Example: 

JournalSize             16M 

0

The 

 tool is very useful to identify and correct file extent 

fragmentation. Reducing extent fragmentation can be very beneficial for 

performance. You can use this utility to determine whether files are 

fragmented, and if so, fix them. If your files are prone to fragmentation 

you should also use the FSM config file tuning options to minimize 

fragmentation. These global configuration settings are 

, 

, and 

. (For more information, see the 

man 

 page.) The 

 man page explains the command 

options in greater detail.

 reporting is another very useful tool. This can show 

you the mix of metadata operations being invoked by client processes, as 

well as latency information for metadata operations and metadata and 

journal I/O. This information is easily accessed in the cvlog log files. All 

of the latency oriented stats are reported in microsecond units.