Bad performance when accessing files over a network share

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Guest

I would like to ask if anyone knows a workaround to our problem. The problem
is bad performance due to a problem with Opportunistic Locking in some
Windows versions. We would need opportunistic locking (oplock) and it is
enabled as works as expected, until the first concurrent client tries to call
LockFileEx on a file someone else has also opened. The problem is documented
in this knowledge base article:

http://support.microsoft.com/?kbid=306981

Whilst not on the list, we verified that this problem persists on Windows
2000 Server SP4 and Windows 2003 Server SP 1 as well.

The problem is that our ISAM database driver uses LockFileEx to lock parts
of the database index files, which in effect will mark this file as
"non-oplockable" as soon as the first concurrent access occurs. I understand
that this LockFileEx call is probably unavoidable because the files are
opened in shared mode to allow write access for concurrent clients to the
same database.

We are already trying to get our hands on an improved ISAM database driver,
but if LockFileEx is unavoidable this would provide no benefit for us.
Accessing the database files locally is also out of question, unfortunately.

Are there any fixes or workarounds to this problem? Do you know any
Microsoft Windows Server versions which aren't affected?

Any help would be appreciated.
 
Attila,

Are you sure that this is the only thing that is affecting youor file
access performance. In 2000 SP4 and in 2003, SMB signing is turned on
by default. This results in a more secure connection, but a 25%
overhead on performance. In cases where there are a large number of
small files being accessed -- banking and imaging applications or some
databases -- this can be even more pronounced with the huge number of
connections made to the files.

You might try turning SBM signing off.

http://support.microsoft.com/default.aspx?scid=kb;en-us;887429

Best Wishes,

Ryan Hanisco
 
Ryan,

This may help us a bit. But we are very certain the problem is that
LockFileEx is incompatible with OpLocks because the performance problem only
happens when at least two users access the same file. Also, we have a
relatively small number of large files in the database, and we open them for
extended amounts of time. We well investigate this anyway, thank you for your
suggestion.

Best regards,
Attila Tajti
 
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