How do the SAM file systems work and how are they configured on the Sunfire cluster?
The SAM file system was designed to optimize the utilization of limited disk space and at the same time provide a dynamic way to do archives and backups. To this end they provide an interface between the files that reside directly on disk, and a tape library such as our L1400. The files system will automatically create copies of files that are freshly written to disk or that are altered. This is to safeguard from disk failures and serves as a standard backup. Additionally, the files system offers the possibility of making further copies on tape, and to keep files that have not been used for an extended period of time on tape altogether. The latter process is called releasing files. Data that have not been accessed for a certain time period may be copied to tape (preferably, more than one copy is made for safety), and then the copy on disk is replaced by a stub, which serves a similar function as inodes in Unix file systems, i.e. it contains information about where the data reside, thei
