AIX 5L Problem Determination - IBM Redbooks

7.4.2 Increasing the file system size
In many instances, the size of a file system needs to be increased because the
demand for storage has increased. In AIX, this is a common procedure, and it is
possible to do by using the chfs command, as in the following example:
# chfs -a size=+300000 /u/testfs
Filesystem size changed to 458752
This example shows how the file system testfs is extended with 300000 512-byte
blocks. When the file system is extended, the logical volume holding the JFS is
also extended, with the number of logical partitions that is needed to fulfill the
space request. If the system does not have enough free space, the volume group
can either be extended with an additional physical volume, or the size specified
for the chfs command must be lowered so that it matches the number of free
LPs.
7.4.3 File system verification and recovery
The fsck command checks and interactively repairs inconsistent file systems.
You should run this command before mounting any file system. You must be able
to read the device file on which the file system resides (for example, the /dev/hd0
device).
Normally, the file system is consistent, and the fsck command merely reports on
the number of files, used blocks, and free blocks in the file system. If the file
system is inconsistent, the fsck command displays information about the
inconsistencies found and prompts you for permission to repair them. If the file
system cannot be repaired, restore it from backup.
Mounting an inconsistent file system may result in a system crash. If you do not
specify a file system with the FileSystem parameter, the fsck command will
check all the file systems with the attribute check=TRUE in /etc/filesystems.
Note: By default, the /, /usr, /var, and /tmp file systems have the check
attribute set to false (check=false) in their /etc/filesystems stanzas. The
attribute is set to false for the following reasons:
► The boot process explicitly runs the fsck command on the /, /usr, /var, and
/tmp file systems.
► The /, /usr, /var, and /tmp file systems are mounted when the /etc/rc file is
run. The fsck command will not modify a mounted file system, and fsck
results on mounted file systems are unpredictable.
152 IBM ^ Certification Study Guide - AIX 5L Problem Determination Tools and Techniques