AIX Basics: Growing a Filesystem

This begins what will be an ongoing series of posts relating to basic AIX tasks.  The first is a quick explanation of how to add and takeaway space from a filesystem:

# df -g
Filesystem GB blocks Free %Used Iused %Iused Mounted on
/dev/hd4 3.00 2.73 10% 11642 2% /
/dev/hd2 4.00 1.90 53% 50028 10% /usr
/dev/hd9var 3.00 1.14 62% 7020 3% /var
/dev/hd3 3.00 1.76 42% 964 1% /tmp
/dev/fwdump 1.00 1.00 1% 4 1% /var/adm/ras/platform
/dev/hd1    3.00    3.00    1%    14    1%    /home

Check the VG for available space.

# lsvg rootvg
VOLUME GROUP:      rootvg                  VG IDENTIFIER:
VG STATE:                    active                    PP SIZE: 512 megabyte(s)
VG PERMISSION:      read/write           TOTAL PPs: 558 (285696 megabytes)
MAX LVs:                       256                        FREE PPs: 454 (232448 megabytes)
LVs:                                    14                         USED PPs: 104 (53248 megabytes)
…

Now, we add space to our filesystem.

# chfs -a size=+5G /home
Filesystem size changed to 16777216

# df -g
Filesystem GB blocks Free %Used Iused %Iused Mounted on
/dev/hd4 3.00 2.73 10% 11642 2% /
/dev/hd2 4.00 1.90 53% 50028 10% /usr
/dev/hd9var 3.00 1.14 62% 7020 3% /var
/dev/hd3 3.00 1.76 42% 963 1% /tmp
/dev/fwdump 1.00 1.00 1% 4 1% /var/adm/ras/platform
/dev/hd1     8.00     7.99     1%     14 1%     /home

Alternatively, we could specify the total size of our filesystem.

# chfs -a size=10G /home
Filesystem size changed to 20971520

# df -g
Filesystem GB blocks Free %Used Iused %Iused Mounted on
/dev/hd4 3.00 2.73 10% 11642 2% /
/dev/hd2 4.00 1.90 53% 50028 10% /usr
/dev/hd9var 3.00 1.14 62% 7020 3% /var
/dev/hd3 3.00 1.76 42% 963 1% /tmp
/dev/fwdump 1.00 1.00 1% 4 1% /var/adm/ras/platform
/dev/hd1    10.00    9.99    1%    14    1%    /home

Be careful when removing space from a filesystem.  It is possible to lose data if the filesystem is close to full, depending on how much you want to decrease by.  This can only be done with JFS2 filesystems.

# chfs -a size=8G /home

or

# chfs -a size=-2G /home

# df -g
Filesystem GB blocks Free %Used Iused %Iused Mounted on
/dev/hd4 3.00 2.73 10% 11642 2% /
/dev/hd2 4.00 1.90 53% 50028 10% /usr
/dev/hd9var 3.00 1.14 62% 7020 3% /var
/dev/hd3 3.00 1.76 42% 963 1% /tmp
/dev/fwdump 1.00 1.00 1% 4 1% /var/adm/ras/platform
/dev/hd1    8.00    7.99    1%    14    1%    /home