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CHAPTER 4 The UNIX File System

4.2 File System Types

SunOS has 3 different types of file systems: disk-based, distributed, and pseudo. The disk-based file systems include hard disks, CDROMs, and diskettes. The distributed file systems manage network resources. The pseudo file systems are memory-based and do not use any disk space. They provide access to kernel information and facilities.
File System Types
TypeNameDescriptionSunOS 4.1.XSunOS 5.X
Disk-basedufsUNIX File System, based on BSD Fat Fast File System (default)yes (known as 4.2)yes
 hsfsHigh Sierra File System, used by CDROMs and supports Rock Ridge extensions. Very similar to ufs, except that it does not support writable media or hard linksyesyes
 pcfsPC File System, to allow read/write access to DOS formatted disksyesyes
 cachefsCache File System, allows use of local disk to store frequently accessed data from a remote file system or CDROMnoyes
DistributednfsNetwork File System, the default distributed file system typeyesyes
 rfsRemote File Share, AT&Ts RFS productyesno (only < 5.3)
 autofsAutomount File System, automounts NFS file systems, as needed, using NIS and NIS+ mapsnoyes
PseudotmpfsTemporary File System, file storage in memory and swap without the overhead of writing to a ufs fileyesyes
 specfsSpecial File System, allows access to the special character and block devicesyesyes
 lofsLoopback File System, creates a virtual file system which can overlay or duplicate existing files. The files are accessible from either pathyesyes
 tfsTranslucent File System, allows mounting of a file system on top of existing files, with both visibleyesno
 procProcess Access File System, allows access to active processes and their imagesnoyes
 fdfsFile Descriptor File System, allows access to file names using descriptorsnoyes
 namefsName File System, used by STREAMS for dynamic mounts of file descriptors on top of filesnoyes
 fifosFirst In First Out File System, allows process access to named pipe filesnoyes
 swapfsSwap File System, used by the kernel to manage swap spacenoyes

4.2.1 - Temporary File System (tmpfs)
4.2.2 - Translucent File System (TFS)
4.2.3 - Swapfs
4.2.4 - Cachefs
4.2.5 - Autofs

Unix System Administration - 8 AUG 1996
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