MacOS X Leopard (10.5) doesn’t save resource fork information (._ hidden files) on the Isilon by default. Leopard uses the Isilon SMB Alternate Data Streams (ADS) feature which allows metadata such as resource fork data to be stored. However, MacOS X Tiger (10.4) cannot use ADS. Therefore, files (without extensions) written to the Isilon from Leopard(10.5) cannot be identified by Tiger (10.4) unless ADS is disabled. [...]