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StorNext File System Tuning
The Metadata Controller System
16 StorNext File System Tuning Guide
•Large value for FSM threads SUMMARY max busy indicates the FSM
configuration setting
ThreadPoolSize is insufficient.
• Extremely high values for FSM cache SUMMARY inode lookups, TKN
SUMMARY TokenRequestV3
, or TKN SUMMARY TokenReqAlloc might
indicate excessive file fragmentation. If so, the
snfsdefrag utility can
be used to fix the fragmented files.
•The VOP and TKN summary statistics of the form count avg/q+e
min/q+e max/q+e show microsecond queue and execution latency
for the various metadata operations. This shows what type of
metadata operations are most prevalent and most costly. These are
also broken out per client, which can be useful to identify a client
that is disproportionately loading the FSM.
SNFS supports the Windows Perfmon utility. This provides many useful
statistics counters for the SNFS client component. To install, obtain a
copy of
cvfsperf.dll from the SCM team in Denver and copy it into the c:/
winnt/system32 directory on the SNFS client system. Then run
rmperfreg.exe and instperfreg.exe to set up the required registry settings.
After these steps, the SNFS counters should be visible to the
Windows
Perfmon utility. If not, check the Windows Application Event log for
errors.
The cvcp utility is a higher performance alternative to commands such
as
cp and tar. The cvcp utility achieves high performance by using
threads, large I/O buffers, preallocation, stripe alignment, DMA I/O
transfer, and Bulk Create. Also, the
cvcp utility uses the SNFS External
API for preallocation and stripe alignment. In the directory-to-directory
copy mode (for example,
cvcp source_dir destination_dir,) cvcp
conditionally uses the
Bulk Create API to provide a dramatic small file
copy performance boost. However, it will not use
Bulk Create in some
scenarios, such as non-root invocation, managed file systems, quotas,
or Windows security. Hopefully, these limitations will be removed in a
future release. When
Bulk Create is utilized, it significantly boosts
performance by reducing the number of metadata operations issued.
For example, up to 20 files can be created all with a single metadata
operation. For more information, see the
cvcp man page.
The cvmkfile utility provides a command line tool to utilize valuable
SNFS performance features. These features include preallocation, stripe
alignment, and affinities. See the
cvmkfile man page.
The Lmdd utility is very useful to measure raw LUN performance as well
as varied I/O transfer sizes.