remote_nfs_swap(5)                                       remote_nfs_swap(5)
                          Tunable Kernel Parameters



 NAME    [Toc]    [Back]
      remote_nfs_swap - enable swapping across NFS

 VALUES    [Toc]    [Back]
    Default
      0 (off)

    Allowed values    [Toc]    [Back]
      0 (off) or 1 (on)

 DESCRIPTION    [Toc]    [Back]
      This tunable controls adding a NFS filesystem for use as swap.  If
      remote_nfs_swap is set to 0 (off), only local filesystems and devices
      can be used for swap.  If it is set to 1 (on), both local and
      networked file systems can be used for swap.

      Historically, this tunable was used in NFS clusters that are no longer
      supported, but this capability has not yet been removed.

    Who Is Expected to Change This Tunable?
      Anyone.

    Restrictions on Changing    [Toc]    [Back]
      Changes to this tunable take effect on the next boot.

    When Should the Tunable Be Turned On?
      Almost never.  As previously mentioned, this tunable was designed for
      systems which are not in use today.  Only systems with extremely
      robust NFS capabilities should even consider using NFS for swap.

    What Are the Side Effects of Turning the Tunable On?
      If the value is set to 1 (on), and a NFS partition is added as swap,
      then some kernel memory will be set aside for NFS transactions to the
      swap file system.  The kernel will then use the NFS swap partition
      just the same as a local file system.  If the NFS capabilities of the
      system are not robust, this could lead to extremely long swap times
      (both swap in and swap out), and possibly a loss of memory because all
      the reserved memory and more could be used by NFS (just when memory
      pressure is high) causing the need for swap.

    When Should the Tunable Be Turned Off?
      Unless you are positive that the NFS system can handle the load of
      being used as swap, and does not have a local file system or disk
      drive to spare, this tunable should always be set to 0 (off).

    What Are the Side Effects of Turning the Tunable Off?
      Any previously defined NFS swap filesystems will no longer be allowed.
      Kernel memory will not be reserved for NFS transactions due to swap.

    What Other Tunables Should Be Changed at the Same Time?
      None.



 Hewlett-Packard Company            - 1 -      HP-UX 11i Version 2: Sep 2004






 remote_nfs_swap(5)                                       remote_nfs_swap(5)
                          Tunable Kernel Parameters



 WARNINGS    [Toc]    [Back]
      All HP-UX kernel tunable parameters are release specific.  This
      parameter may be removed or have its meaning changed in future
      releases of HP-UX.

      Installation of optional kernel software, from HP or other vendors,
      may cause changes to tunable parameter values.  After installation,
      some tunable parameters may no longer be at the default or recommended
      values.  For information about the effects of installation on tunable
      values, consult the documentation for the kernel software being
      installed. For information about optional kernel software that was
      factory installed on your system, see HP-UX Release Notes at
      http://docs.hp.com.

 AUTHOR    [Toc]    [Back]
      remote_nfs_swap was developed by HP.


 Hewlett-Packard Company            - 2 -      HP-UX 11i Version 2: Sep 2004