6.1 Release Notes
Release Notes for Red Hat Enterprise Linux 6.1
Copyright © 2011 Red Hat.
The text of and illustrations in this document are licensed by Red Hat
under a Creative Commons Attribution–Share Alike 3.0 Unported license
("CC-BY-SA"). An explanation of CC-BY-SA is available at http://creativecommons.org/licenses/by-sa/3.0/
In accordance with CC-BY-SA, if you distribute this document or an
adaptation of it, you must provide the URL for the original version.
Red Hat, as the licensor of this document, waives the right to
enforce, and agrees not to assert, Section 4d of CC-BY-SA to the fullest
extent permitted by applicable law.
Red Hat, Red Hat Enterprise Linux, the Shadowman logo, JBoss,
MetaMatrix, Fedora, the Infinity Logo, and RHCE are trademarks of Red
Hat, Inc., registered in the United States and other countries.
Linux® is the registered trademark of Linus Torvalds in the United States and other countries.
Java® is a registered trademark of Oracle and/or its affiliates.
XFS® is a trademark of Silicon Graphics International Corp. or its subsidiaries in the United States and/or other countries.
MySQL® is a registered trademark of MySQL AB in the United States, the European Union and other countries.
All other trademarks are the property of their respective owners.
1801 Varsity Drive
Raleigh, NC 27606-2072 USA
Phone: +1 919 754 3700
Phone: 888 733 4281
Fax: +1 919 754 3701
Red Hat Enterprise Linux minor releases are an aggregation of
individual enhancement, security and bug fix errata. The Red Hat
Enterprise Linux 6.1 Release Notes documents the major changes made to
the Red Hat Enterprise Linux 6 operating system and its accompanying
applications for this minor release. Detailed notes on all changes in
this minor release are available in the Technical Notes
Naming convention for network interfaces
Traditionally, network interfaces in Linux are named
However, in many cases, these names do not correspond to actual labels
on the chassis. Modern server platforms with multiple network adapters
can encounter non-deterministic and counterintuitive naming of these
Red Hat Enterprise Linux 6.1 introduces biosdevname, an optional convention for naming network interfaces. biosdevname assigns names to network interfaces based on their physical location. Note, however that biosdevname is disabled by default, except for a limited set of Dell systems.
The implementation of version 3.0 of the Universal Serial Bus (USB
3.0) specification is a fully supported feature in Red Hat Enterprise
Linux 6.1. USB 3.0 support was previously considered a Technology
Preview in previous releases.
CPU and Memory Hot-add
On Nehalem-EX, hot-adding of CPUs and memory is now fully supported
in Red Hat Enterprise Linux 6.1. Note, however that the hardware must
also support hot-adding. Damage may occur from an attempt to hot-add
CPUs or memory on hardware without support for hot-adding.
Red Hat Enterprise Linux 6.1 features a wide range of driver updates, including updates to the following device drivers:
ixgbe driver for Intel 10 Gigabit PCI Express Network devices
mlx4 driver for Mellanox ConnectX HCA InfiniBand hardware, providing support for Mellanox Connect X2/X3 10GB devices
be2net driver for ServerEngines BladeEngine2 10Gbps network devices
bnx2 driver for Broadcom NetXtreme II
network devices, including support for Advanced Error Reporting (AER),
and PPC support for 5709 devices
bnx2i driver for Broadcom NetXtreme II iSCSI
bnx2x driver for Broadcom Everest network devices
ixgbevf Virtual Function drivers
tg3 driver for Broadcom Tigon3 ethernet devices
bfa driver for Brocade Fibre Channel to PCIe Host Bus Adapters
bna driver for Brocade 10G PCIe ethernet Controllers
cxgb4 driver for Chelsio Terminator4 10G Unified Wire Network controllers
be2iscsi driver for ServerEngines BladeEngine 2 Open iSCSI devices
be2net driver for ServerEngines BladeEngine2 10Gbps network devices
lpfc driver for Emulex Fibre Channel HBAs
e1000e drivers for Intel PRO/1000 network devices
Intel Iron Pond ethernet driver
Intel Kelsey Peak Wireless driver
Intel SCU driver
megaraid_sas driver for LSI MegaRAID SAS controllers
mpt2sas driver for the SAS-2 family of adapters from LSI Logic
The kernel shipped in Red Hat Enterprise Linux 6.1 includes several
hundred bug fixes for and enhancements to the Linux kernel. For details
concerning every bug fixed in and every enhancement added to the kernel
for this release, refer to the kernel chapter in the Red Hat Enterprise Linux 6.1 Technical Notes.
Control groups are a feature of the Linux kernel introduced in Red
Hat Enterprise Linux 6. Each control group is a set of tasks on a system
that have been grouped together to better manage their interaction with
system hardware. Control groups can be tracked to monitor the system
resources that they use. Additionally, system administrators can use
control group infrastructure to allow or to deny specific control groups
access to system resources such as memory, CPUs (or groups of CPUs),
networking, I/O, or the scheduler.
Red Hat Enterprise Linux 6.1 introduces many improvements and updates
to control groups, including the ability to throttle block device
Input/Output (I/O) to a particular device, either by bytes per second or
I/O Per Second (IOPS).
Additionally, integration with libvirt and other userspace tools is
provided by the new ability to create hierarchical block device control
groups. The new block device control group tunable
group_idle, provides better throughput with control groups while maintaining fairness.
Red Hat Enterprise Linux 6.1 also introduces the new autogroup feature, reducing latencies and allowing for more interactive tasks during CPU intensive workloads. This cgsnapshot tool, providing the ability to take a snapshot of the current control group configuration.
Control Groups and other resource management features are discussed in detail in the Red Hat Enterprise Linux 6 Resource Management Guide
Red Hat Enterprise Linux 6.1 introduces support for Receive Packet
Steering (RPS) and Receive Flow Steering (RFS). Receive Packet Steering
allows incoming network packets to be processed in parallel over
multiple CPU cores. Receive Flow Steering chooses the optimal CPU to
process network data intended for a specific application.
kdump is an advanced crash dumping mechanism. When enabled, the
system is booted from the context of another kernel. This second kernel
reserves a small amount of memory, and its only purpose is to capture
the core dump image in case the system crashes.
Red Hat Enterprise Linux 6.1 introduces the kernel message dumper,
which is called when a kernel panic occurs. The kernel message dumper
provides easier crash analysis and allows 3rd party kernel message
logging to alternative targets.
Performance updates and improvements
The kernel in Red Hat Enterprise Linux 6.1 provides the following notable performance improvements:
Updates and improvements to Transparent Huge Pages (THP) support
Updates to perf_event, adding the new perf lock feature to better analyze lock events.
kprobes jump optimization, reducing overhead and enhancing SystemTap performance.
Updates to i7300_edac and i7core_edac, providing support for monitoring of memory errors on motherboards using Intel 7300 chipset
Red Hat Enterprise Linux 6.1 provides a range of updates for graphics
hardware. The driver for Intel Generation 6 Graphics on the Sandy
Bridge processor is introduced in this release, providing fully
accelerated 2D and 3D graphics on these devices. Additionally, this
release introduces support for the Matrox MGA-G200ER graphics chipset.
Red Hat Enterprise Linux 6.1 introduces the
video driver to support the XGI Z9S AND Z11 chipsets. The SIS driver
that provided support for older XGI hardware is no longer being updated
to support new hardware.
Monitors that do not supply Extended Display Identification Data
(EDID) to the operating system now have a default resolution of 1024 x
NetworkManager is the desktop tool that is used to set up, configure
and manage a wide range of network connection types. In Red Hat
Enterprise Linux 6.1, NetworkManager has improved support for the
configuration of Wi-Fi Protected Access (WPA) Enterprise and Internet
Protocol version 6 (IPv6).
Red Hat Enterprise Linux 6.1 provides updated Advanced Linux Sound Architecture - High Definition Audio (ALSA-HDA) drivers.
LVM Snapshots of Mirrors
The LVM snapshot feature provides the ability to create backup images
of a logical volume at a particular instant without causing a service
interruption. When a change is made to the original device (the origin)
after a snapshot is taken, the snapshot feature makes a copy of the
changed data area as it was prior to the change so that it can
reconstruct the state of the device. In Red Hat Enterprise Linux 6.1 the
ability to take a snapshot of a mirrored logical volume is a fully
LVM Stripe of Mirrors
It is now possible to combine RAID0 (striping) and RAID1 (mirroring)
in a single logical volume in LVM. Creating a logical volume while
simultaneously specifying the number of mirrors ('--mirrors X') and the
number of stripes ('--stripes Y') results in a mirror devices whose
constituent devices are striped.
5. Authentication and Interoperability
System Security Services Daemon (SSSD)
The System Security Services Daemon (SSSD) implements a set of
services for central management of identity and authentication.
Centralizing identity and authentication services enables local caching
of identities, allowing users to still identify in cases where the
connection to the server is interrupted. SSSD supports many types of
identity and authentication services, including: Red Hat Directory
Server, OpenLDAP, 389, Kerberos and LDAP. SSSD in Red Hat Enterprise
Linux 6.1 is updated to version 1.5, providing the following bug fixes
Improved online/offline detection
Improved LDAP access-control provider with support for shadow and authorizedService
Improved caching and cleanup logic for different schemata
Improved DNS based discovery
Automatic Kerberos ticket renewal
Enablement of the Kerberos FAST protocol
Better handling of password expiration
The Deployment Guide
contains a section that describes how to install and configure SSSD.
Red Hat Enterprise Linux 6.1 features IPA as a Technology Preview.
IPA is an integrated security information management solution which
combines Red Hat Enterprise Linux, Red Hat Directory Server, MIT
Kerberos, and NTP. It provides web browser and command-line interfaces,
and its numerous administration tools allow an administrator to quickly
install, set up, and administer one or more servers for centralized
authentication and identity management.
Samba is an open source implementation of the Common Internet File
System (CIFS) protocol. It allows the networking of Microsoft Windows,
Linux, UNIX, and other operating systems together, enabling access to
Windows-based file and printer shares. Samba in Red Hat Enterprise Linux
6.1 is updated to version 3.5.6.
Samba in Red Hat Enterprise Linux 6.1 allows users to use their own
Kerberos credentials when accessing CIFS mount, rather than needing the
same mount credentials for all access to the mount.
FreeRADIUS is an Internet authentication daemon, which implements the
RADIUS protocol, as defined in RFC 2865 (and others). It allows Network
Access Servers (NAS boxes) to perform authentication for dial-up users.
FreeRADIUS in Red Hat Enterprise Linux 6.1 is updated to version
Kerberos is a networked authentication system which allows users and
computers to authenticate to each other with the help of a trusted third
party, the KDC. In Red Hat Enterprise Linux 6.1, Kerberos (supplied by
the krb5 package) is updated to version 1.9.
OpenSCAP is a set of open source libraries that support the Security
Content Automation Protocol (SCAP) standards from the National Institute
of Standards and Technology (NIST). OpenSCAP supports the SCAP
Common Vulnerabilities and Exposures (CVE)
Common Platform Enumeration (CPE)
Common Configuration Enumeration (CCE)
Common Vulnerability Scoring System (CVSS)
Open Vulnerability and Assessment Language (OVAL)
Extensible Configuration Checklist Description Format (XCCDF)
Additionally, the openSCAP package includes an application to
generate SCAP reports about system configuration. openSCAP is now a
fully supported package in Red Hat Enterprise Linux 6.1.
Smartcard support for SPICE
The Simple Protocol for Independent Computing Environments (SPICE) is
a remote display protocol designed for virtual environments. SPICE
users can view a virtualized desktop or server from the local system or
any system with network access to the server. Red Hat Enterprise Linux
6.1 introduces support for smartcard passthough via the SPICE protocol.
The Security Guide
assists users and administrators in learning the processes and
practices of securing workstations and servers against local and remote
intrusion, exploitation and malicious activity.
Installation and boot support is added in Red Hat Enterprise Linux 6.1
for the Emulex 10GbE PCI-E Gen2 and Chelsio T4 10GbE network adapters.
Additionally, the GRUB bootloader is updated with support for booting
volumes with a 4KB sector size on UEFI systems.
The installer in Red Hat Enterprise Linux 6.1 will detect unsupported
hardware platforms and provide a notification to the user. The
installation will continue, but the following message is displayed
This hardware (or a combination thereof) is not supported by Red Hat. For more information on supported hardware, please refer to http://www.redhat.com/hardware.
Improved support for iSCSI adapters
Red Hat Enterprise Linux 6.1 features improved support for iSCSI
adapters at installation and boot time, including the ability to
separate login credentials for iSCSI storage during installation and
support for offload iSCSI adapters (e.g. the Emulex Tiger Shark
Red Hat Enterprise Linux 6 supports installation over iSCSI using
auto-detection of BIOS iSCSI settings in iBFT. However, reconfiguration
of the iBFT settings after installation was not possible. In Red Hat
enterprise Linux 6.1, TCP/IP settings and iSCSI initiator configuration
are dynamically configured from iBFT settings during boot time.
SystemTap is a tracing and probing tool that allows users to study
and monitor the activities of the operating system (particularly, the
kernel) in fine detail. It provides information similar to the output of
tools like netstat, ps, top, and iostat; however, SystemTap is designed
to provide more filtering and analysis options for collected
SystemTap in Red Hat Enterprise Linux 6.1 is updated to version 1.4, providing:
GNU Project Debugger (GDB)
The GNU Project Debugger (normally referred to as GDB) debugs
programs written in C, C++, and other languages by executing them in a
controlled fashion, and then printing out their data. GDB in Red Hat
Enterprise Linux 6.1 is updated to version 7.2, providing many bugfixes
and enhancements, including enhancements to the python scripting
features, and C++ debugging enhancements.
Performance Application Programming Interface (PAPI)
Red Hat Enterprise Linux 6.1 introduces the Performance Application
Programming Interface (PAPI). PAPI is a specification of a
cross-platform interfaces to hardware performance counters on modern
microprocessors. These counters exist as a small set of registers that
count events, which are occurrences of specific signals related to a
processor's function. Monitoring these events has a variety of uses in
application performance analysis and tuning.
OProfile is a system-wide profiler for Linux systems. The profiling
runs transparently in the background and profile data can be collected
at any time. In Red Hat Enterprise Linux 6.1, OProfile is updated to
version 0.9.6-12, providing support for AMD family 12h/14h/15h
processors and Intel Westmere specific events.
Valgrind is an instrumentation framework for building dynamic
analysis tools that can be used to profile applications in detail.
Valgrind tools are generally used to automatically detect many memory
management and threading problems. The Valgrind suite also includes
tools that allow you to build new profiling tools to suit your needs.
Red Hat Enterprise Linux 6.1 provides Valgrind version 3.6.0.
GNU Compiler Collection (GCC)
The GNU Compiler Collection (GCC) includes, among others, C, C++, and
Java GNU compilers and related support libraries. Red Hat Enterprise
Linux 6 features version 4.4 of GCC, which includes the following
features and enhancements:
The libdfp library is updated in Red Hat Enterprise Linux 6.1. libdfp
is a decimal floating point math library, and is available as an
alternative to the glibc math functions on Power and s390x
architectures, and is available in the supplementary channels.
Eclipse is a powerful development environment that provides tools for
each phase of the development process. It is integrated into a single,
fully configurable user interface for ease of use, featuring a pluggable
architecture which allows for extension in a variety of ways.
An updated version of the Eclipse development environment is available
in Red Hat Enterprise Linux 6.1, providing the following updates and
All the major plugins are refreshed, including Valgrind and OProfile integration and the tools for working with C and C++
The Mylyn task-focused framework is updated
Enhanced resource filtering for workspace contents
performance enhancements when working with C, C++ and Java code bases
New IcedTea Web Open Source Web Browser Plugin and Webstart implementation for OpenJDK.
Clusters are multiple computers (nodes) working in concert to increase
reliability, scalability, and availability to critical production
services. High Availability using Red Hat Enterprise Linux 6 can be
deployed in a variety of configurations to suit varying needs for
performance, high-availability, load balancing, and file sharing.
The following major updates to clustering are available in Red Hat Enterprise Linux 6.1
Rgmanager now supports the concept of critical and non-critical resources
System Administrators can now configure and run a cluster using
command line tools. This feature provides an alternative to manually
editing the cluster.conf configuration file or using the graphical
configuration tool, Luci.
Red Hat Enterprise Linux High Availability on Red Hat Enterprise Linux KVM hosts is fully supported
Comprehensive SNMP Trap support from central cluster daemons and sub-parts
Additional watchdog integration allows a node to reboot itself when it loses quorum
The development library packages provided in the High Availability,
Load Balancer, and Resilient Storage Add-On channels are not considered
supported nor are their ABIs or APIs guaranteed to be consistent.
The Cluster Suite Overview
document provides an overview of Red Hat Cluster Suite for Red Hat Enterprise Linux 6. Additionally, the High Availability Administration
document describes the configuration and management of Red Hat cluster systems for Red Hat Enterprise Linux 6.
The new host kernel networking backend, vhost, is a fully supported feature in Red Hat Enterprise Linux 6.1. vhost provides superior throughput and latency over the userspace implementation.
The qcow2 image format now supports caching of metadata.
Additionally, support is added for live snapshots using external qcow2
Block I/O latency improvements
ioeventfd is now available, providing faster notification of block I/O.
Kernel SamePage Merging (KSM)
The KVM hypervisor in Red Hat Enterprise Linux 6 features Kernel
SamePage Merging (KSM), allowing KVM guests to share identical memory
pages. Page sharing reduces memory duplication, allowing a host with
similar guest operating systems to run more efficiently.
KSM in Red Hat Enterprise Linux 6.1 is Transparent HugePage aware. KSM
has the ability to scan subpages inside hugepages and split them when
merging is possible.
Additionally, KSM enablement can now be controlled on a per-VM basis.
PCI device assignment improvements
PCI configuration space access is improved, enabling a broader set of PCI devices to be device-assigned to guest VMs.
In Red Hat Enterprise Linux 6.1, the Time Stamp Counter (TSC)
synchronization can now be automatically detected on guest bootup or
when a host CPU is hot-plugged. Additionally, the TSC synchronization
frequency is adjusted after a live migration.
Additionally, the new
drive_del command allows libvirt to safely remove a block device from a guest.
General Updates and Improvements
The maximum display resolution on qemu-kvm is now 2560x1600 pixels
Red Hat Enterprise Linux 6.1 includes the ability to expose an
emulated Intel HDA sound card to all guests. This update enables native
sound support for many guests including the 64-bit version of Windows 7
QEMU char device flow control is enabled
Message Signaled Interrupts (MSI) implemented for the win-virtio-blk driver
A new standard interface for selecting/prioritizing the boot devices of the guest
Stability improvements for live migration
QEMU userspace static tracing
Virtual disk online dynamic resize feature
Forbid pci hot unplug of critical devices such as gpu, pci bus controller, isa bus controller
Red Hat Subscription Manager and the Subscription Service
Effective software and infrastructure management requires a mechanism
to handle the software inventory — both the type of products and the
number of systems that the software is installed on. In parallel with
Red Hat Enterprise Linux 6.1, Red Hat is introducing a new subscription
service which provides oversight for the software subscriptions for an
organization and a more effective content delivery system.
On local systems, the new Red Hat Subscription Manager offers both GUI
and command-line tools to manage the local system and its allocated
subscriptions. A better method to handle subscriptions will help our
customers allocate their subscriptions more effectively and will make
installing and updating Red Hat products much simpler.
In Red Hat Enterprise Linux 6.0 and 5.6 and older, subscriptions were based on access to channels and were assigned to an organization as a whole. Starting in Red Hat Enterprise Linux 6.1, subscriptions are based on installed products
and are assigned to systems individually. This provides clear and
delineated control over the products used by and subscribed to by a
As part of the new subscription structure, the Customer Portal
provides two paths to manage subscriptions: Certificate-based Red Hat
Network, which uses the new subscription service, and RHN Classic, which
uses the traditional channels. Systems must be managed either by the
new Certificate-based Red Hat Network or by RHN Classic, but not both.
If a system was previously managed by RHN Classic, there is no direct,
supported migration path from RHN Classic to Certificate-based Red Hat
Automated Bug Reporting Tool
Red Hat Enterprise Linux 6 introduced the new Automated Bug Reporting
Tool (ABRT). ABRT logs details of software crashes on a local system,
and provides interfaces (both graphical and command line based) to
report issues to Red Hat support. In Red Hat Enterprise Linux 6.1, ABRT
is updated to version 1.1.16. This update provides an enhanced graphical
user interface (GUI) in addition to a range of other bugfixes and
openCryptoki contains version 2.11 of the PKCS#11 API, implemented
for IBM Cryptocards. openCryptoki is updated in Red Hat Enterprise Linux
6.1, providing many bugfixes and enhancements, including better overall
OpenLDAP is an open source suite of Lightweight Directory Access
Protocol (LDAP) applications and development tools. OpenLDAP in Red Hat
Enterprise Linux 6.1 is updated to version 2.4.23. This updated version
of OpenLDAP utilizes Network Security Services (NSS) cryptographic
libraries, replacing OpenSSL.
TigerVNC provides client and server software for Virtual Network
Computing (VNC). VNC is a remote display system, allowing a user to view
a computing desktop environment over a network connection.TigerVNC is
updated to version 1.1.0, providing many bugfixes enhanced encryption
tuned is a system tuning daemon that monitors system components and
dynamically tunes system settings. Utilizing ktune (the static mechanism
for system tuning), tuned can monitor and tune devices (e.g. hard disk
drives and ethernet devices). In Red Hat Enterprise Linux 6.1, the tuned
tuning profiles now include support for the s390x architectures.
A. Revision History
|Revision 0-39||Fri May 20 2011|
|Copyedit in the Installation section|
|Revision 1-0||Tue Mar 22 2011|
|Initial Version of the Red Hat Enterprise Linux 6.1 Release Notes|