There is a new trove method available in trunk now called "null-aio". It can be selected by putting "TroveMethod null-aio" in the <StorageHints> section of the file system configuration file.

This is only useful for debugging purposes, because it deliberately skips doing any file I/O on the server side. Please use with caution! It does all metadata operations the same as any other method, but file reads will return garbage and file writes are thrown away. Writing beyond eof triggers a truncate to mimic the appropriate resulting bstream size.

This might be useful once in a while for narrowing down performance problems between network and storage. It takes the storage out of the loop and shows approximately what the network is capable of by itself. Of course it will only work for benchmarks that don't verify data correctness (or otherwise rely on data read off of PVFS).

We used to have a compile time option (--disable-disk-io) for this same purpose, but that actually hasn't worked in a while. Nowadays its easier to just do this as a trove method that can be selected at runtime without recompiling.

-Phil
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