Hello there,

   We're facing troubles (exceptions during treatment, corrupted databases, 
...) when using the SERIALIZED file_lock mode on databases that reside on a 
network shared folder. The issue happens randomly. We excluded the 
concurrent access reason because we got some corrupted databases with one 
single user accessing the database from a single JVM process. We then used 
the unit tests of H2 src/test/org/h2/test/unit/TestFileLockSerialized.java. 
They execute nicely on our Windows desktops. But when changing 
TestBase.BASE_TEST_DIR in order to reference a networked directory instead 
of a local one, they fail on testBigDatabase with cache activated (got 
assertion "Expected: 500 actual: 999") or on testThreeMostlyReaders (got 
duplicate key exception) for instance. They fail randomly but nearly every 
time. I guess the serialized lock mode is sensitive to timing and the 
result may depend on the responsiveness of the network. We use 1 Gbs 
Ethernet with Novell network but our customers can have slightly different 
LANs. We noted that some parameters like WRITE_DELAY=0 or setting the new 
h2.modifyOnWrite property to true make things better but the unit tests 
still fails from time to time when executed on a networked database.
   We may use a real H2 server in some cases but the SERIALIZED mode is 
really the easier way to deploy a database for most of our customers and we 
would really appreciate if we could use it. We understand there's a 
counterpart in performance. However, our problem here is not performance 
(which is pretty good) but the integrity of the database. We manage to 
reproduce the failure with networked database but the same issues could 
potentially happen with a local database under similar circumstances 
(strong solicitation compared to file system responsiveness).
   Does anybody encounter the same problems when using database on a LAN ?
   Are there any other tests we can run on our network or any trace to 
retrieve in order to give more useful information ?
   Any help will be greatly appreciated.

Laurent RICHARD

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