Multiple domain web hosting - 2. Everything is a File server, a journalized
2. Everything is a File server, a journalized file system such as ext3 is preferred. reiserfs, perhaps because of its genesis, is more suited to a database server. JFS is preferred in cases were file system throughput is the main issue. XFS is interesting if you need any of its advanced features. For normal use, these four file systems give approximately the same results and all of them have different options to tune the file system for a particular use. Please refer to the file system’s documentation for more information. 2. Everything is a File We introduced the file ownership and permissions access concepts, but really un derstanding the UNIXfile system (and this also applies to Linux’s file systems) requires that we redefine the concept of What is a file . Here, everything really means everything. A hard disk, a partition on a hard disk, a parallel port, a connection to a web site, an Ethernet card: all these are files. Even directories are files. Linux recognizes many types of files in addition to the standard files and directories. Note that by file type here, we do not mean the type of content of a file: for GNU/Linux and any UNIX system, a file, whether it be a PNG image, a binary file or whatever, is just a stream of bytes. Differentiating files according to their contents is left to applications. 2.1. The Different File Types When you issue ls -l, the character before the access rights identifies the file type. We have already seen two types of files: regular files (-) and directories (d). You can also find other types if you wander through the file tree and list the contents of directories: 1. Character mode files: they are either special system files (such as /dev/null, which we have already discussed), or peripherals (serial or parallel ports), which share the trait that their contents (if they have any) are not buffered (meaning they are not kept in memory). Such files are identified by the letter c. 2. Block mode files: these files are peripherals, and unlike character files, their contents are buffered. For example, some files in this category are: hard disks, partitions on a hard disk, floppy drives, CD-ROM drives and other storage devices. Files like /dev/hda, /dev/sda5 are examples of block-mode files. Such files are identified by the letter b. 3. Symbolic links: these files are very common and heavily used in the Mandriva Linux system start-up procedure (see Chapter 37, The Start-Up Files: init