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StorNext File System Tuning
The Metadata Controller System
StorNext File System Tuning Guide 15
JournalSize 0
The optimal settings for JournalSize are in the range between 16M and
64M, depending on the FsBlockSize. 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.
The following table shows recommended settings. Choose the setting that
corresponds to your configuration.
This setting is adjustable using the
cvupdatefs utility. For more
information, see the
cvupdatefs man page.
Example:
JournalSize 16M
SNFS Tools 0
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
FsBlockSize JournalSize
16KB 16MB
64KB 64MB