QFS
From Wikipedia, the free encyclopedia
QFS is a filesystem sold by Sun Microsystems. It is tightly integrated with SAM, the Storage and Archive Manager, and hence is often referred to as SAM-QFS. SAM provides the functionality of a Hierarchical Storage Manager.
QFS supports some volume management capabilities, allowing many disks to be grouped together into a file system. File system metadata can be kept on a separate set of disks, which is useful for streaming applications where long disk seeks cannot be tolerated.
SAM extends the QFS file system transparently to archival storage. A QFS file system may have a relatively small (gigabytes to terabytes) "disk cache" backed by petabytes of tape or other bulk storage. Files are copied to archival storage in the background, and transparently retrieved to disk when accessed. QFS supports up to four archival copies, each of which can be on disk, tape, or optical media, or may be stored at a remote site also running QFS.
Shared QFS adds multi-host functionality, allowing multiple machines to read & write the same disks at the same time through the use of multi-ported disks or a storage area network. (QFS also has a single-writer mode which can be used when disks can be shared between hosts but a network connection is not permissible; this is often used in content distribution applications, as the internet-connected hosts need not be connected to an internal network.)
QFS was originally developed by LSC, Incorporated, which was purchased by Sun in 2001.
