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StorNext File System Tuning
The Metadata Controller System
StorNext File System Tuning Guide 15
This setting is adjustable using the cvupdatefs utility. For more
information, see the
cvupdatefs man page.
Example: JournalSize 16M
SNFS Tools The snfsdefrag 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
InodeExpandMin,
InodeExpandInc, and InodeExpandMax. (For more information, see the
man
cvfs_config page.) The snfsdefrag man page explains the command
options in greater detail.
FSM hourly statistics 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.
It also possible to trigger an instant FSM statistics report by setting the
Once Only debug flag using cvadmin. For example:
cvadmin -F snfs1 -e ‘debug 0x01000000’ ; tail -100 /usr/
cvfs/data/snfs1/log/cvlog
The following items are a few things to watch out for:
• A non-zero value for FSM wait SUMMARY journal waits indicates
insufficient IOPS performance of the disks assigned to the metadata
stripe group. This usually requires reducing the metadata I/O latency
time by adjusting RAID cache settings or reducing bandwidth
contention for the metadata LUN. Another possible solution is to
add another metadata stripe group to the file system. This will
improve metadata ops performance through I/O concurrency.
• Non-zero value for FSM wait SUMMARY free buffer waits or low hit
ratio for
FSM cache SUMMARY buffer lookups indicates the FSM
configuration setting
BufferCacheSize is insufficient.
• Non-zero value for FSM wait SUMMARY free inode waits or low hit
ratio for
FSM cache SUMMARY inode lookups indicates the FSM
configuration setting
InodeCacheSize is insufficient.