Quantum 6-01376-05 manual InodeCacheSize, ThreadPoolSize, ForcestripeAlignment, FsBlockSize

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The Metadata Controller System

InodeCacheSize

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

ThreadPoolSize

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 max threads FSM hourly statistic reported in the cvlog file.

Example: ThreadPoolSize 32 # default 16, 512 KB memory per thread

ForcestripeAlignment

This setting should always be set to Yes. This is critical if the largest StripeBreadth defined is greater than 1MB. Note that this setting is not adjustable after initial file system creation.

Example: ForcestripeAlignment Yes

FsBlockSize

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

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