filesystems
Purpose
Centralizes file system characteristics.
Description
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 single parti-
tion. All of the information about the file system is
centralized in the filesystems file. Most of the file
system maintenance commands take their defaults from this
file. The file is organized into stanzas whose names are
file system names and whose contents are attribute-value
pairs specifying characteristics of the file system.
The filesystems file serves two purposes:
o It documents the layout characteristics of the file
systems.
o 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 informa-
tion is defined in the file.
File System Attributes
Each stanza names the directory where the file system is
normally mounted. The attributes specify all of the
parameters of the file system. See "attributes" for the
format of an attribute file. The attributes currently
used are:
account Used by the dodisk command to determine the
file systems to be processed by the
accounting system. This value can be either
true or false.
backupdev Used by the backup and restore commands to
determine the default output device associ-
ated with each file system. The value of
this keyword is usually the name of a
diskette or magnetic tape special file.
backuplen Used by the backup command to determine the
size of the default backup device associated
with each file system. The size of a tape is
measured in tracks times feet. For example,
the backuplen for a 300-foot 9-track tape is
2700. This parameter is ignored for
diskettes.
backuplev Used by the backup command to determine the
default backup level to take for each file
system. Backup levels are discussed in the
backup command.
boot Used by the mkfs command to initialize the
boot block of a new file system. This speci-
fies the name of the load module to be placed
into the first block of the file system.
check Used by the fsck command to determine the
default file systems to be checked. true
enables checking while false disables
checking. If a number, rather than true is
specified, the file system is checked in the
specified pass of checking. Multiple pass
checking, described in fsck command in AIX
Operating System Commands Reference, permits
multiple file systems to be checked in par-
allel when multiple drives exist.
cluster Specifies the number of 512-byte disk blocks
that the system treats as a unit. Only one
or two values are supported. The RT PC
default values are 4 for non-removable disks
and 1 for removable disks.
cyl Used by the mkfs command to initialize the
free list and superblock of a new file
system. The value is the number of blocks in
one cylinder. It defines the size of an
interleave cluster.
dev Identifies, for local mounts, either the
block special file where the file system
resides or the file or directory to be
mounted. System management utilities use
this attribute to map file system names to
the corresponding device names. For remote
mounts, identifies the file or directory to
be mounted.
free Used by the df command to determine which
file systems are to have their free space
displayed by default. This value is either
true or false.
mount Used by the mount command to determine
whether or not this file system should be
mounted by default. The possible values of
mount are:
automatic Automatically mounts a file
system when the system is
rebooted. For example, in the
sample file, the root file
system line is mount=automatic.
This means the root file system
mounts automatically when the
system is rebooted. The true
value is not used so that mount
all does not try to mount it.
Also, the value is not false
because certain utilities, such
as ncheck, normally avoid file
systems with a value of
mount=false.
false This file system is not mounted
by default.
inherit When a remote file system is
mounted, inherit mounts any
additional file systems con-
tained in the specified file
system. This allows the local
node to duplicate the file
system structure of the server
node, starting at the specified
mount point.
readonly When mount=false,readonly is
specified, the file system is
mounted as read-only.
removable If mount=true,removable is
specified, a diskette file
system is automatically mounted
when its files are opened and
unmounted when the opened files
are closed. Also notice that
in the example, this file is
shipped designating two remov-
able file systems, one having
asterisks. The asterisks indi-
cate commented lines in the
file. The mkdir command must
be used to create a directory
in order to mount file system
/dev/fd1.
true This file system is mounted by
the mount all command.
nodename Used by the mount command to determine which
node contains the remote file system. If
this attribute is not present, the mount is a
local mount. The value of nodename can be
either a valid node nickname or a valid node
ID. This value can be overridden with the
mount -n command.
size Used by the mkfs command for reference and to
build the file system. The value is the
number of blocks in the file system.
skip Used by the mkfs command to initialize the
free list and superblock of a new file
system. The value is the number of blocks to
skip when the free list is interleaved. This
number is processor- and device-specific.
type Used by the mount command to determine
whether or not this file system should be
mounted. When the command "mount -t" string
is issued, all of the currently unmounted
file systems with a type equal to string are
mounted.
vcheck Used by the varyon command to determine which
file systems to check. The value true
enables checking while false disables
checking.
vmount Used by the varyon command to determine
whether this file system should be mounted by
default. The values of vmount are: true,
the varyon command mounts the file system, or
false, the file system is not mounted by
default.
vol Used by the mkfs command when initializing
the label on a new file system. The value is
a volume or pack label using a maximum of six
characters. The file system label is always
the stanza name.
Example
*
* File system information
*
default:
vol = "AIX"
mount = false
check = false
free = false
backupdev = /dev/rfd0
backuplen = 2400
/:
dev = /dev/hd0
vol = "root"
mount = automatic
check = true
free = true
/u:
dev = /dev/hd1
vol = "/u"
mount = true
check = true
free = true
/u/joe/1:
dev = /u/joe/1
mount = inherit
nodename = vance
/usr:
dev = /dev/hd2
vol = "/usr"
mount = true
check = true
free = true
/tmp:
dev = /dev/hd2
vol = "/tmp"
mount = true
check = true
free = true
/diskette0:
dev = /dev/fd0
mount = true,removable
* /diskette1:
* dev = /dev/fd1
* mount = true,removable
File
/etc/filesystems
Related Information
In this book: "attributes" and "fs."
The backup, df, fsck, mkfs, mount, restore, and umount
commands in AIX Operating System Commands Reference.