StorNext File System Tuning
The Metadata Controller System
12 StorNext File System Tuning Guide
BufferCacheSize
This setting consumes up to 2X bytes of memory times the number
specified. Increasing this value can reduce latency of any metadata
operation by performing a hot cache access to directory blocks, inode
information, and other metadata info. This is about 10 to 1000 times
faster than I/O. It is especially important to increase this setting if
metadata I/O latency is high, (for example, more than 2ms average
latency). We recommend sizing this according to how much memory is
available; more is better. Optimal settings for BufferCacheSize range
from 16MB to 128MB.
Example: # BufferCacheSize 64M # default 32MB
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. Optimal settings for InodeCacheSize
range from 16K to 128K.
Example: InodeCacheSize 16K # 1000-1200 bytes each, default
8K
ThreadPoolSize
This setting consumes up to 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. Optimal settings for ThreadPoolSize range from 32K to 128K.