| There is a crisis in disks today. The FAT (file
allocation table), which is the file system used on all
DOS PCs, doesn't use all the space on them. Because the
FAT has a fixed number of sectors, it must increase their
size as disks get larger. Cairo will introduce an improved file system that can address logical mass-storage devices as large as 408 million TB. That's about 418 billion GB or 427 trillion MB. But the real challenge for future file systems is to make it easier for users to manage their mass storage. Already, people are losing track of files on 200-MB hard drives. It's obvious that the current model of organizing files into more deeply nested thickets of directories and subdirectories simply won't keep up. Files aren't just files anymore. With compound documents, files may contain embedded objects in diverse formats that are linked to the applications that created them. For example, a Microsoft Word document might contain tables linked to Excel and pictures linked to Paintbrush. If you want to view all the Excel tables you created over the past six months, today's file systems are inadequate because the smallest items they catalog and retrieve are files, not objects. Users need a finer-grained file system that lets them find, retrieve, and manipulate objects independently of the file structure. Microsoft's answers to these problems are OLE structured storage and OFS (Object File System), an extension to NTFS (NT File System). OLE structured storage is like a file system within a file. The compound file is subdivided into a tree structure of subfiles called stream objects and sub-subdirectories called storage objects. Your data is stored in the streams; storage objects may contain streams or other storage objects. This might appear to complicate matters even further, because it adds yet another tree to the file hierarchy. That's where OFS comes in. Microsoft recently announced OLE DB, an interface layer that connects OLE to back-end databases. That database can be a flat-file database, a relational database, or a file system organized like a database. In effect, OFS will be a relational database that can be searched and sorted using tried-and-true query methods. OFS is extensible, so you (or a program) could add new fields. Today's DOS FAT has only a few fields for such attributes as time/date stamps, file size, and read/write flags. But OFS could have fields that store the name of the person who created the file or object, the formats of the objects, or just about anything else that would help you manage your information. Some elements of this technology are found in Unix, OpenVMS, System 7.5, the Newton OS, and OpenDoc's Bento-format compound files. Indeed, even some current Windows applications (e.g., Word) let you tag a file with additional attributes. But for most PC users, OFS will be the biggest leap forward in file management since the introduction of subdirectories in DOS 2.0. And the implications for corporate data systems are even more remarkable by enabling the tracking and searching of data in compound documents. Copyright 1994-1998 BYTE |