Red Hat GFS 5.2.1 -, Administrator'S Manual

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104 Chapter 9. Managing GFS
Variable
Specifies a special reserved name from a list of values (refer to Table 9-5) to represent one of
multiple existing files or directories. This string is not the name of an actual file or directory
itself. (The real files or directories must be created in a separate step using names that correlate
with the type of variable used.)
LinkName
Specifies a name that will be seen and used by applications and will be followed to get to one of
the multiple real files or directories. When
LinkName
is followed, the destination depends on
the type of variable and the node or user doing the following.
Variable Description
@hostname
This variable resolves to a real file or directory named with the hostname string
produced by the following command entry:
echo ’uname -n’
@mach
This variable resolves to a real file or directory name with the machine-type string
produced by the following command entry:
echo ’uname -m’
@os
This variable resolves to a real file or directory named with the operating-system
name string produced by the following command entry:
echo ’uname -s’
@sys
This variable resolves to a real file or directory named with the combined machine
type and OS release strings produced by the following command entry:
echo
’uname -m’_’uname -s’
@uid
This variable resolves to a real file or directory named with the user ID string
produced by the following command entry:
echo ’id -u’
@gid
This variable resolves to a real file or directory named with the group ID string
produced by the following command entry:
echo ’id -g’
Table 9-5. CDPN
Variable
Values
9.13.2. Example
In this example, there are three nodes with hostnames
n01
,
n02
and
n03
. Applications on each node
uses directory
/gfs/log/
, but the administrator wants these directories to be separate for each node.
To do this, no actual log directory is created; instead, a
@hostname
CDPN link is created with the
name
log
. Individual directories
/gfs/n01/
,
/gfs/n02/
, and
/gfs/n03/
are created that will be
the actual directories used when each node references
/gfs/log/
.
n01#
cd /gfs
n01#
mkdir n01 n02 n03
n01#
ln -s @hostname log
n01#
ls -l /gfs
lrwxrwxrwx 1 root root 9 Apr 25 14:04 log -> @hostname/
drwxr-xr-x 2 root root 3864 Apr 25 14:05 n01/
drwxr-xr-x 2 root root 3864 Apr 25 14:06 n02/
drwxr-xr-x 2 root root 3864 Apr 25 14:06 n03/
n01#
touch /gfs/log/fileA
n02#
touch /gfs/log/fileB
n03#
touch /gfs/log/fileC