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HP-UX System Administrator's Guide: Routine Management Tasks: HP-UX 11i Version 3 > Chapter 6 Managing System Performance

Making Changes


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Increasing the Number of nfsd Daemons

To increase the number of nfsds running on a server, do the following steps:

  1. Edit /etc/rc.config.d/nfsconf, raising the value of NUM_NFSD; for example:


  2. Stop and restart the nfs.server script:

    /sbin/init.d/nfs.server stop

    /sbin/init.d/nfs.server start

Defragmenting an HFS File System

Defragmenting an HFS file system could improve throughput by reducing disk seek time. In practice, though, most experts believe it will usually make little or no difference to performance. You should do it only if you have good reason to believe, or have received expert advice, that your system will really benefit.

NOTE: This applies only to HFS file systems. JFS file systems do need to be defragmented regularly. See “Defragmenting a JFS File System”.

You can defragment an HFS file system by backing it up to tape, removing and recreating it, then recovering the data from the tape.

The example that follows shows an alternative method, using dcopy, and assumes you have enough disk space to create a new logical volume at least as large as /dev/vg01/lvol8. We’ll operate on the /work file system, which resides on the logical volume /dev/vg01/lvol8.

  1. Back up the file system; for example,

    tar cv /work

    backs up /work to the system default tape device, /dev/rmt/0m.

  2. Create a new logical volume (see HP-UX System Administrator) but do not mount it to any file system.

    We’ll assume this new logical volume is /dev/vg01/lvol9.

  3. Make sure no one has files open in /work and that it is no one’s current working directory, for example:

    fuser -cu /work

  4. Unmount /work:

    umount /work

  5. Write out the contents of /work to /dev/vg01/lvol9:

    dcopy -v /dev/vg01/rlvol8 /dev/vg01/lvol9

    NOTE: The source file system should be a raw device (/dev/vg01/rlvol8) and the destination file system should be a block device (/dev/vg01/lvol9).
  6. Mount the new logical volume to the mount point of the original file system, /work:

    mount /dev/vg01/lvol9 /work

    You can now reuse the original logical volume /dev/vg01/lvol8) or remove it (see “Removing a Logical Volume”).

Defragmenting a JFS File System

To maintain performance, particularly on file systems with very large files, JFS provides the means to reorder disk space to regain contiguous areas on which to write files. This process of defragmentation should be performed periodically.

To defragment a JFS file system using HP SMH

  1. Access the HP SMH Homepage as root.

  2. Select Tools, Disks and File Systems, File Systems. This will display a list of file systems.

  3. Select the desired JFS (VxFS) file system. You can now display extent or directory fragmentation for the file system, or click on the Defragment Extents... or Defragment Directories... actions on the right side of the page.

For more information, consult HP SMH’s online help.

To defragment a JFS file system using fsadm

Execute the following to perform both directory and extent reorganization and to generate reports before and after reorganization:

fsadm -d -D -e -E /mount_point

For detailed information, consult fsadm_vxfs(1M).

Daily Defragmentation

To maintain optimal performance on busy file systems, it may be necessary to defragment them nightly.

For example, to defragment every evening at 9 p.m. all the extents and directories within the file system mounted at /home, include the following entry in a file used by cron(1M):

0 21 * * * fsadm -d -e /home

Configurable Kernel Parameters

In some cases, you may be able to get the results you need by resetting kernel parameters. For example, if a user frequently runs out of processes (symptom no more processes), raising the value of maxuprc might be the answer.

NOTE: Tunable kernel parameters can be static or dynamic (not requiring a system reboot or kernel rebuild). The list of dynamic tunables is continually growing. To determine which tunables are dynamic on your system, use the kmtune command (see the kmtune(1M) manpage), or see the Kernel Configuration portion of HP SMH. In HP SMH’s Tunables screen. You can tell at a glance whether or not the value of a particular tunable can be changed without a reboot.

Use the kctune command or the kcweb web interface. See kctune(1M) and kcweb(1M).

Configuring Kernel Tunable Parameters Using HP SMH

  1. Access the HP System Management Homepage (HP SMH) as root.

  2. Select Tools, Kernel Configuration, Tunables. This will display the Kernel Configuration page with the Tunables tab displayed.

  3. Click on the Modify Tunable action on the right side of the page. This will display the Modify Tunable page.

  4. You can now reset the tunable default, enter a new value, or log comments.

  5. Click on Modify to complete the change.

For more information on dynamic tunables, see HP-UX System Administrator’s Guide: Configuration Management and the Dynamically Tunable Kernel Parameters in HP-UX 11i whitepaper at http://docs.hp.com.

CAUTION: Make sure you read the help for all the parameters related to any parameter you are considering changing. In the case of maxuprc, you would need to read the help on nproc as well as maxuprc.
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