Solaris File Systems
Back on track,VxFS from Veritas, and Sun's QFS provided a number of advantages over UFS, the biggest advantage was the ability to cater for extremely large files and file systems. With UFS the maximum for files and file systems is a terabyte, whilst VxFS and QFS offered petrabytes.
The following table gives a small sample of regular disk-based file systems:-
|UFS||The Berkeley fat fast file system (default for Solaris)|
|VxFS||Veritas file system|
|QFS||LCS's file system|
|PCFS||MS-DOS fat file system, usually associated with floppy dsks|
|HSFS||High Sierra file system, usually associated with CD-ROMs|
|UDFS||Universal Disk Fomat, associated with DVDs|
|TMPFS||Temporary file system (usually memory based and used for swapping|
For the 3 file systems I work with, this table provides a small comparison
|Maximum file size||1TB||8,000 TB||1PB|
|Maximum file system size||1TB||8,000 TB||1PB|
|Allocation based method||Block||Extent||Extent|
|Logging||Y (metadta)||Y (metadata)||N|
|Direct I/O||Y (Solaris 2.6 onwards)||Y||Y|
Whilst differences exist between UFS and it's high-capacity neighbours, not just whether the file system is block or extent based, but whether files are extended a block at a time or a number of blocks at a time. Another difference recently raises it's head and that is the support for hierarchal storage management (HSM) in which data flows transparently between faster online and slower near-line media when it has not been recently accessed. HSM although not available for UFS works very well with VXFS and QFS.
if you need a file system that is greater than 1TB or maybe that you require additional functionality/features then you may want to read this interesting article which has an insight into trade-offs for using these and other file systems.
PCFS provided the means and support for the implementation for MS-DOS FAT file system for use mainly with floppy disks.
HSFS (aka ISO 9660) commonly associated CD-ROMs. A bonus under Solaris is that HSFS also supported the Rock Ridge extentions to provided unix-style file naming.
With the introduction of Solaris 8 we see the support for UDFs namly support for DVD devices.
TMPFS may look and act like a disk-based file system, but they are actually resident in memory.
The primary goal o /tmp is for memory swappig. IE memory is not written to disk unless physical memory is exhausted, therefore /tmp are only temporary storage areas.. I'll discuss swapping a little later in another post.
NFS (the network file system) common across almost all operating systems provides a file-sharing mechanism across a network and across different platforms.
[part 2 - pseudo file systems]