Manage swap space in rhel5 __server

One, add swap space:

1. Extend an existing swap space:

<1> prohibit the swap space in use first:

[Root@server4 ~]# Swapoff/dev/mapper/tools-swap

<2>, re-resize/dev/mapper/tools-swap:

[Root@server4 ~]# LVM lvresize/dev/tools/swap-l +300m
Extending logical volume Swap to 500.00 MB
Logical Volume swap successfully resized

<3> reformatting using Mkswap:

[Root@server4 ~]# Mkswap/dev/tools/swap
Setting up Swapspace version 1, size = 524283 KB

<4>, enable swap:

[Root@server4 ~]# Swapon-av
Swapon On/dev/mapper/tools-swap

<5> View Swap Size:

  [root@server4 ~]# cat/proc/swaps
filename                                  type            size     used    Priority
/dev/sda3                                 partition       1044216 0      -2
/ dev/mapper/tools-swap                   partition       511992  0       -4

[Root@server4 ~]# Free-m
Total used free shared buffers Cached
mem:194 172 21 0 19 78
-/+ buffers/cache:75 119
swap:1519 0 1519

2. Add a new swap space (based on LVM):

[Root@server4 ~]# LVM lvcreate tools-n swap1-l 100M
Logical volume "Swap1" created
[Root@server4 ~]# Mkswap/dev/tools/swap1
Setting up Swapspace version 1, size = 104853 k

Change/etc/fstab file and join/dev/tools/swap1.

To enable the newly created swap space:

[Root@server4 ~]# Swapon-av
Swapon On/dev/mapper/tools-swap1

[Root@server4 ~]# Free-m
Total used free shared buffers Cached
mem:194 173 20 0 19 78
-/+ buffers/cache:75 118
swap:1619 0 1619

3. Create swap file:

[Root@server4/]# dd If=/dev/zero of=/swapfile bs=1k count=102400
102400+0 Records in
102400+0 Records out
104857600 bytes (MB) copied, 1.23157 seconds, 85.1 MB/s

[Root@server4/]# Mkswap/swapfile
Setting up Swapspace version 1, size = 104853 KB

[Root@server4/]# Swapon/swapfile

Add the following line to the/etc/fstab file:

/swapfile Swap Defaults 0 0

Second, delete swap space:

1. Reduce a swap space:

[root@server4/]# swapoff/dev/mapper/tools-swap
[root@server4/]# lvm lvreduce/dev/tools/swap-l -400M
  ; Warning:reducing Active Logical Volume to 100.00 MB
  i DESTROY YOUR DATA (filesystem etc.)
Do your really want to reduce swap? [y/n]: y
  reducing logical volume swap to 100.00 MB
  Logical Volume swap successfully resized
[roo T@server4/]# mkswap/dev/tools/swap
Setting up swapspace version 1, size = 104853 KB
[root@server4/]# Swapon-va
Swapon On/dev/mapper/tools-swap

[Root@server4/]# LVs
LV VG Attr lsize Origin snap% move Log copy% Convert
Swap Tools-wi-ao 100.00M
Swap1 Tools-wi-ao 100.00M

2. Remove an LVM-based swap:

[Root@server4/]# Swapoff/dev/tools/swap1
[Root@server4/]# LVM Lvremove/dev/tools/swap1
Do your really want to remove active logical Volume "SWAP1"? [y/n]: Y
Logical volume "Swap1" successfully removed

Then remove it from the/etc/fstab file.

3. Delete a swap file:

[Root@server4/]# swapoff-v/swapfile

[Root@server4/]# Rm-rf/swapfile