RHBA-2009:1422 - Bug Fix Advisory

Topic

An updated ktune package that fixes a bug is now available.

Description

The ktune package includes settings for server performance-tuning.

This updated ktune package fixes the following bug:

• when running a Red Hat Enterprise Linux KVM guest under heavy load, the

guest's system clock had the tendency to drift by an amount correlated with
the system load. This ktune update provides an interactive Bourne shell
script, fix_clock_drift.sh, which, when run as the superuser, inspects
various system parameters to determine if the guest on which it is run is
susceptible to clock drift under load and, if so, then creates a new
"grub.conf.kvm" file in the /boot/grub/ directory. This file contains a
kernel boot line with additional kernel parameters that allow the kernel to
account for and prevent significant clock drift on the KVM guest. Note also
that the ntpd service must be running on the KVM guest for the clock drift
to be corrected.

Important: after running fix_clock_drift.sh as the superuser, and once the
script has created the "grub.conf.kvm" file, then the guest's current
"grub.conf" file should be backed up manually by the system administrator,
the new "grub.conf.kvm" file should be manually inspected to ensure that it
is identical to "grub.conf" with the exception of the additional boot line
parameters, the "grub.conf.kvm" file should finally be renamed "grub.conf",
and the guest should be rebooted. (BZ#518039)

Users of Red Hat Enterprise Linux KVM guests that are affected by
significant clock drift are advised to upgrade to this updated package,
which resolves this issue.

Solution

Before applying this update, make sure that all previously-released
errata relevant to your system have been applied.

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 518039 - need script to set kernel parameters that fix clock drift

CVEs

(none)

References

(none)