File system types supported by AIX

A file system is a complete directory structure, including a root ( / ) directory and any directories and files beneath it. A file system is confined to a logical volume. All of the information about the file system is centralized in the /etc/filesystems file. Most of the file system maintenance commands take their defaults from this file. The file is organized into stanza names that are file system names and contents that are attribute-value pairs specifying characteristics of the file system. AIX provides powerful tools for management of disks and file systems. This is accomplished through the use of JFS (Journaled File System) and LSM (Logical Storage Manager).

The filesystems file serves two purposes:
  1. It documents the layout characteristics of the file systems.
  2. It frees the person who sets up the file system from having to enter and remember items such as the device where the file system resides, because this information is defined in the file.

AIX supports two types of file systems

Local File Systems

Journaled File System (JFS)
A journaling file system allows for quick file system recovery after a crash occurs by logging the metadata of files. By enabling file system logging, the system records every change in the metadata of the file into a reserved area of the file system. The actual write operations are performed after the logging of changes to the metadata has been completed.

Enhanced Journaled File System (JFS2)
Enhanced JFS, or JFS2, is another native AIX journaling file system that was introduced in AIX 5.1. Enhanced JFS is the default file system for 64-bit kernel environments. Due to address space limitations of the 32–bit kernel, Enhanced JFS is not recommended for use in 32-bit kernel environments.

CD ROM File System
A CD ROM file system is a read-only file system that is stored on CD ROM media. AIX supports several types of CD-ROM File Systems. Please refer to AIX documentation for more details.

RAM file system
A RAM disk is a simulated disk drive that resides in memory. RAM disks are designed to have significantly higher I/O performance than physical drives, and are typically used to overcome I/O bottlenecks with nonpersistent files. The maximum size of a RAM file system is limited by the amount of available system memory. You can create a file system on the RAM disk device to make it available for normal file system usage. Do not use RAM disks for persistent data, as all data is lost if the system crashes or reboots.

Remote File Systems

Network File System
The Network File System, or NFS, is a distributed file system that allows you to access files and directories located on remote computers and treat those files and directories as if they were local. For example, you can use operating system commands to create, remove, read, write, and set file attributes for remote files and directories.

Name File System (NameFS)
NameFS provides the function of file-over-file and directory-over-directory mounts (also called soft mounts) that allows you to mount a subtree of a file system in a different place in the file name space, allowing a file to be accessed through two different path names. A NameFS file system is a purely logical entity. It exists only during the time it is mounted, and serves only as a means of grouping files for logical reasons. All operations on an object accessed through NameFS are implemented by the physical file system type that contains it and the function and semantics of that file system apply as if there were no interposing NameFS.

Also Read: Storage Area Network (SAN) Basic Free Tutorials

General Parallel File System
The General Parallel File System, or GPF, is a high-performance, shared-disk file system that can provide fast data access to all nodes in a server cluster. Parallel and serial applications access files using standard UNIX file system interfaces, such as those in AIX. GPFS provides high performance by striping I/O across multiple disks, high availability through logging, replication, and both server and disk failover.

Most used AIX File System Commands

  • Remove mount point entry and the LV for /mount1
rmfs /mount1 (Add -r to remove mount point)
  • Grow the /var filesystem by 1 Gig 
chfs -a size=+1G /var
  • Grow the /var filesystem to 1 Gig 
chfs -a size=1G /var
  • Find the file usage on a filesystem
du -smx /
  • List filesystems in a grep-able format
  • Get extended information about the /home filesystem
lsfs -q /home
  • Create a log device on datavg VG
 mklv -t jfs2log -y datalog1 datavg 1
  • Format the log device just created
 logform /dev/datalog1

Default AIX File Systems

/dev/hd1                 /home
/dev/hd2                 /usr
/dev/hd3                 /tmp
/dev/hd4                 /                                                 root
/dev/hd5                                                                   BLV (Boot Logical Volume)
/dev/hd6                                                                   Paging Space
/dev/hd8                                                                   JFS2 log
/dev/hd9var            /var
/dev/hd10opt          /opt
/dev/hd11admin     /admin                                        New from 6.1
livedump                /var/adm/ras/livedump               New in 6.1 TL3
                              /proc                                           procfs pseudo filesystem

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