On Sat, Apr 05, 2008 at 06:52:27PM +0530, Manish Katiyar wrote: > ExtX has optional features that are organized into three categories > based on what the operating system should do if it encounters a file > system with a feature that it does not support. The first category is > the compatible features, and if the OS does not support one of these > features, it can still mount the file system and continue as normal. > Examples of this include allocation methods, the existence of a file > system journal, and extended attributes. There are also incompatible > features, and if an OS encounters one of these, it should not mount > the file system. An example of this includes compression. Lastly, a > feature can be a read only compatible feature. When an OS encounters > one of these features that it does not support, the file system should > be mounted as read only. Examples of this include large file support > and using B-trees to sort directories instead of an unsorted list. > > In above I could not understand what is meant by OS supported ??? > Isn't for a filesystem the features are filesystem specific. or OS > here means the VFS layer ??? How can an OS support or not support > B-trees or journalling, it has to be filesystem dependant......isn't > it ? If the OS doesn't support journalling (i.e.: doesn't support ext3 which basically is ext2+journalling), it can still mount the filesystem as an ext2 filesystem. Therefore journalling is a compatible feature. Erik -- Erik Mouw -- mouw@xxxxxxxxxxxx
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