POLYCENTER Advanced File System

The POLYCENTER Advanced File System (AdvFS), which consists of a file system that ships with the base system and a set of file system utilities that are available as a separate, layered product, is a log-based (journaled) file system that is especially valuable on systems with large amounts of storage. Because it maintains a log of active file-system transactions, AdvFS avoids lengthy file system checks on reboot and can therefore recover from a system failure in seconds. AdvFS ensures that log records are written to disk before data records, ensuring that file domains (file systems) are recovered to a consistent state. AdvFS uses extent-based allocation for optimal performance.

To users and applications, AdvFS looks like any other UNIX file system. It is compliant with POSIX and SPEC 1170 file-system specifications. AdvFS file domains and other Digital UNIX file systems, like UFS, can exist on the same system and are integrated with the Virtual File System (VFS) and the Unified Buffer Cache (UBC). AdvFS file domains can also be remote-mounted with NFS and support extended file attributes (XFAs). For more information on XFAs, see the section called Virtual File System.

In addition to providing rapid restart and increased file-system integrity, AdvFS supports files and file systems much larger than 2 GBs and, by separating the file system directory layer from the logical storage layer, provides increased file-system flexibility and manageability.

In addition to the Advanced File System that ships as part of the base operating system, the POLYCENTER Advanced File System Utilities are available as a layered product. The AdvFS Utilities enable a system administrator to create multivolume file domains, add and remove volumes online, clone filesets for online backup, unfragment and balance file domains online, stripe individual files, and establish trashcans so that users can restore their deleted files. The AdvFS Utilities also provide a Graphical User Interface for configuring and managing AdvFS file domains. The AdvFS Utilities require a separate license Product Authorization Key (PAK). Contact your Digital representative for additional information on the AdvFS Utilities product. For more information on AdvFS, see the System Administration guide and the POLYCENTER Advanced File System Utilities Technical Summary.