Quantum 6-01376-05 User Manual

  StorNext File System Tuning

The Metadata Controller System

StorNext File System Tuning Guide

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This setting

consumes about 800-1000 bytes of memory times the number 

specified. Increasing this value can reduce latency of any metadata 

operation by performing a hot cache access to inode information instead 

of an I/O to get inode info from disk, about 100 to 1000 times faster. It is 

especially important to increase this setting if metadata I/O latency is 

high, (for example, more than 2ms average latency). You should try to 

size this according to the sum number of working set files for all clients. 

The recommended range is 16K to 64K. 
Example: 

InodeCacheSize          16K     # 800-1000 bytes each, default 8K

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This setting consumes 512 KB memory times the number specified. 

Increasing this value can improve concurrency of metadata operations. 

For example, if many client processes are executing concurrently, the 

thread pool can become exhausted by I/O wait time. Increasing the 

thread pool size permits hot cache operations to be processed that would 

otherwise be backed up behind the I/O-bound operations. There are 

various O/S limits to the number of threads that can cause fatal problems 

for the FSM daemon, so it's not a good idea to set this setting too high. A 

range from 32 to 128 is recommended, depending on the amount of 

available memory. It is recommended to size it according to the 

 FSM hourly statistic reported in the 

 file.

Example:

 ThreadPoolSize          32      # default 16, 512 KB memory per thread

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This setting should always be set to Yes. This is critical if the largest 

 defined is greater than 1MB. Note that this setting is not 

adjustable after initial file system creation.
Example: 

ForcestripeAlignment    Yes 

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The optimal settings are in the range of 4K, 8K, 16K, or 32K. Settings 

greater than 32K can adversely impact performance because metadata I/

O operations are performed less efficiently. Any value greater than 4K