- File systems tie everything together
- each file system is a consistent view of storage - protection, access,
operations, metadata and so on
- there may be (usually are) several file systems in an os
- three major classes of file systems
- local file systems - ntfs, ext2 or ext3
- remote file systems - nfs, sms
- non-file systems - /proc
- The file manager provides a uniform interface to all the file systems
- a virtual file system binds the different file systems together
- storage
- generally, a single storage device is divided into partitions
- each partition is a contiguous group of cylinders on a disk
- good for accounting (who owns what), autonomous management (separate
quota or protection policies), reliability (replicated and
independent metadata), performance (swap partitions)
- partitioning has extra overhead, can fragment access patterns,
causing performance loss
- each partition holds a file system
- sometimes, a file system can span partitions (aix)
- file-system code configures an empty partition into a file system
- the superblock or file-control block contains file-system information -
size, directory and metadata locations, bad-sector mappings, spare
sectors, boot information
- file systems can impose more structure on partitions - cylinder groups
in bsd unix; clusters in nt; performance related
- pasting together file systems
- tree-shaped hierarchies - paste the root of one file system into
another file system
- mounting file systems
- this is a flexible and powerful way to build file systems
- it's relatively simple to do to
- plan 9 carries this to the extreme - per-process file systems, pasted
together from bits and pieces of other file systems
- interesting file systems
- remote file systems
- move the file system to another machine - local and remote proxies
- move the storage device to another machine - san or nas
-
/proc file systems
- access processes as if they were files
- a synthetic file system
This page last modified on 4 December 2002.