How to use the swapoff command
This article explains the features of the HP-UX 11i v3 swapoff command incorporated on the September 2008 release. This command provides the ability to remove swap devices without rebooting the system. This feature is enabled by the command and an enhanced system call swapctl(2):
- "The HP-UX Swapoff command, swapoff(1M), is a Software Pack product and is delivered as an optional product on all Operating Environments. For more information about Software Pack, see “Software Pack (Optional HP-UX 11i v3 Core Enhancements)".
The swapctl(2) system call has been enhanced through patches delivered in the FEATURE11i patch bundle.
This enhancement to the swapctl(2) is automatically delivered through a patch in the September 2008 FEATURE11i bundle. To add the swapon installation of the Swapoff Enhacement bundle is required. This bundle is available on current DVD media and for download at the Software Depot website:
1. Verified that the HP-UX 11i v3 has installed the FEATURE11i bundle.
# swlist -l bundle | grep -e HPUX11i -e FEATURE11i FEATURE11i B.11.31.0809.326a Feature Enablement Patches for HP-UX 11i v3, September 2008 HPUX11i-VSE-OE B.11.31.0803 HP-UX Virtual Server Operating Environment
2. Install the swapoff bundle.
# swinstall -s /var/tmp/swapoff_B.11.31.0809.02_HP-UX_B.11.31_IA_PA.depot \* ======= 11/08/08 22:41:59 MST BEGIN swinstall SESSION (non-interactive) (jobid=zx6000-0015) * Session started for user "root@zx6000". * Beginning Selection * Target connection succeeded for "zx6000:/". * "zx6000:/var/tmp/swapoff_B.11.31.0809.02_HP-UX_B.11.31_IA_PA.depot": Cannot open the logfile on this target or source. Possibly the media is read-only or there is a permission problem. Check the daemon logfile and "/var/tmp/swagent.log" on this host for more information. * Source: /var/tmp/swapoff_B.11.31.0809.02_HP-UX_B.11.31_IA_PA.depot * Targets: zx6000:/ * Software selections: swapoff,r=B.11.31.0809.02,a=HP-UX_B.11.31_IA/PA,v=HP Swapoff.SWAPOFF,r=B.11.31.0809.02,a=HP-UX_B.11.31_IA/PA,v=HP,fr=B.11.31.0809.02,fa=HP-UX_B.11.31_IA Swapoff.SWAPOFF-ENG-MAN,r=B.11.31.0809.02,a=HP-UX_B.11.31_IA/PA,v=HP,fr=B.11.31.0809.02,fa=HP-UX_B.11.31_IA * Selection succeeded. * Beginning Analysis and Execution * Session selections have been saved in the file "/.sw/sessions/swinstall.last". * The analysis phase succeeded for "zx6000:/". * The execution phase succeeded for "zx6000:/". * Analysis and Execution succeeded. NOTE: More information may be found in the agent logfile using the command "swjob -a log zx6000-0015 @ zx6000:/". ======= 11/08/08 22:42:26 MST END swinstall SESSION (non-interactive) (jobid=zx6000-0015)
Complete details of the usage of the swapoff command is described on it's manpage.
# man swapoff swapoff(1M) swapoff(1M) NAME swapoff - online disabling of swap device SYNOPSIS /usr/sbin/swapoff device ... DESCRIPTION The swapoff command disables swapping on the specified swap device(s) for the current boot. (NOTE: the term swap refers to an obsolete implementation of virtual memory; HP-UX actually implements virtual memory by way of paging rather than swapping. This command and others retain names derived from swap for historical reasons.) Notes + The swapoff command will not remove entry from /etc/fstab for the device. The /etc/fstab file needs to be modified to remove the device entries. + The swapoff command is guaranteed to disable the swap devices for the current boot only when the devices were enabled for swapping through swapon (see swapon(1M). + A swap device will not be disabled if the current available system swap space without the device is not sufficient for the system to operate. RETURN VALUE swapoff returns one of the following values: 0 Successful completion. >0 Error condition occurred. EXAMPLE The following example disable paging on block device /usr/sbin/swapoff /dev/dsk/c10t0d0 AUTHOR swapoff was developed by HP. SEE ALSO swapinfo(1M), swapon(1M), swapctl(2), fstab(4). Hewlett-Packard Company - 1 - HP-UX 11i Version 3: May 2008
The following example demostrates the usage of the swapoff to remove swap devices without rebooting the system, an LVM logical volume is used as swap device for the demostration.
# swapinfo -tam Mb Mb Mb PCT START/ Mb TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME dev 12288 0 12288 0% 0 - 1 /dev/vg00/lvol2 reserve - 391 -391 memory 1938 628 1310 32% total 14226 1019 13207 7% - 0 - # lvcreate -L 1024 -n swap2 /dev/vg01 Logical volume "/dev/vg01/swap2" has been successfully created with character device "/dev/vg01/rswap2". Logical volume "/dev/vg01/swap2" has been successfully extended. Volume Group configuration for /dev/vg01 has been saved in /etc/lvmconf/vg01.conf # swapon -p 1 /dev/vg01/swap2 # swapinfo -tam Mb Mb Mb PCT START/ Mb TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME dev 12288 0 12288 0% 0 - 1 /dev/vg00/lvol2 dev 1024 0 1024 0% 0 - 1 /dev/vg01/swap2 reserve - 391 -391 memory 1938 628 1310 32% total 15250 1019 14231 7% - 0 - # swapoff /dev/vg01/swap2 # swapinfo -tam Mb Mb Mb PCT START/ Mb TYPE AVAIL USED FREE USED LIMIT RESERVE PRI NAME dev 12288 0 12288 0% 0 - 1 /dev/vg00/lvol2 reserve - 391 -391 memory 1938 628 1310 32% total 14226 1019 13207 7% - 0 - # lvremove /dev/vg01/swap2 The logical volume "/dev/vg01/swap2" is not empty; do you really want to delete the logical volume (y/n) : y Logical volume "/dev/vg01/swap2" has been successfully removed. Volume Group configuration for /dev/vg01 has been saved in /etc/lvmconf/vg01.conf
- HP-UX 11i Version 3 September 2008 Release Notes: Operating Environments Update Release - Chapter 4 Hardware-Specific Information - HP-UX Swapoff