<P> A file system stores all the metadata associated with the file--including the file name, the length of the contents of a file, and the location of the file in the folder hierarchy--separate from the contents of the file . </P> <P> Most file systems store the names of all the files in one directory in one place--the directory table for that directory--which is often stored like any other file . Many file systems put only some of the metadata for a file in the directory table, and the rest of the metadata for that file in a completely separate structure, such as the inode . </P> <P> Most file systems also store metadata not associated with any one particular file . Such metadata includes information about unused regions--free space bitmap, block availability map--and information about bad sectors . Often such information about an allocation group is stored inside the allocation group itself . </P> <P> Additional attributes can be associated on file systems, such as NTFS, XFS, ext2, ext3, some versions of UFS, and HFS+, using extended file attributes . Some file systems provide for user defined attributes such as the author of the document, the character encoding of a document or the size of an image . </P>

Discuss the general requirements of a file system