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Red Hat EnterpriseLinux 6.1 Beta6.1 Release Notes

Release Notes for Red Hat Enterprise Linux 6.1 Beta

Copyright © 2011 Red Hat.

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6.1 Release Notes

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Phone: 888 733 4281 Fax: +1 919 754 3701

AbstractThe Beta Release Notes provide an overview of the major new features and enhancements in RedHat Enterprise Linux 6.1 Beta.

Note: The Release Notes document a pre-release version of Red Hat Enterprise Linux 6.1. Theincluded information is subject to substantial change, and is provided only as a preview. The includedinstructions should not be considered complete, and should be used with caution.

1. Hardware Support ................................................................................................................... 22. Kernel .................................................................................................................................... 43. Desktop .................................................................................................................................. 54. Storage .................................................................................................................................. 65. Authentication and Interoperability ........................................................................................... 66. Security .................................................................................................................................. 77. Installation .............................................................................................................................. 88. Compiler and Tools ................................................................................................................. 99. Clustering ............................................................................................................................. 1010. Virtualization ....................................................................................................................... 1111. Entitlement .......................................................................................................................... 1212. General Updates ................................................................................................................. 12

A. Technology Previews 13

B. Known Issues 16B.1. Installer ..................................................................................................................... 16B.2. Deployment ............................................................................................................... 16B.3. Virtualization .............................................................................................................. 16B.4. Storage and Filesystems ............................................................................................ 17B.5. Networking ................................................................................................................ 18B.6. Clustering .................................................................................................................. 18B.7. Authentication ............................................................................................................ 18B.8. Devices ..................................................................................................................... 18B.9. Kernel ....................................................................................................................... 18B.10. Desktop ................................................................................................................... 19

C. Revision History 20

1. Hardware Support

1.1. Naming convention for network interfacesTraditionally, network interfaces in Linux are named eth[X]. However, in many cases, these namesdo not correspond to actual labels on the chassis. Modern server platforms with multiple networkadapters can encounter non-deterministic and counterintuitive naming of these network interfaces.

Red Hat Enterprise Linux 6.1 introduces biosdevname, an optional convention for naming networkinterfaces. biosdevname assigns names to network interfaces based on their physical location.

CPU and Memory Hot-add

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Note

In Red Hat Enterprise Linux 6.1 Beta, biosdevname is disabled by default, except for a limited setof the latest Dell systems.

Refer to the Red Hat Knowledge Base1 for further information on using biosdevname.

1.2. CPU and Memory Hot-addOn Nehalem-EX, full hot-adding of CPUs and memory is now fully supported in Red Hat EnterpriseLinux 6.1

1.3. Driver UpdatesRed Hat Enterprise Linux 6.1 features a wide range of driver updates, including updates to thefollowing device drivers:

• ixgbe driver for Intel 10 Gigabit PCI Express Network devices

• mlx4 driver for Mellanox ConnectX HCA InfiniBand hardware, providing support for MellanoxConnect X2/X3 10GB devices

• be2net driver for ServerEngines BladeEngine2 10Gbps network devices

• bnx2 driver for Broadcom NetXtreme II network devices, including support for Advanced ErrorReporting (AER), and PPC support for 5709 devices

• bnx2i driver for Broadcom NetXtreme II iSCSI

• bnx2x driver for Broadcom Everest network devices

• igbvf and ixgbevf Virtual Function drivers

• e1000e driver for Intel PRO/1000 ethernet devices

• 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

• e1000 and e1000e drivers for Intel PRO/1000 network devices

• Intel Iron Pond Ethernet driver

1 https://access.redhat.com/kb/docs/DOC-47318

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• Intel Kelsey Peak Wireless driver

• megaraid_sas driver for LSI MegaRAID SAS controllers

2. Kernel

Control GroupsControl groups are a new feature of the Linux kernel introduced in Red Hat Enterprise Linux 6. Eachcontrol group is a set of tasks on a system that have been grouped together to better manage theirinteraction with system hardware. Control groups can be tracked to monitor the system resourcesthat they use. Additionally, system administrators can use control group infrastructure to allow or todeny specific control groups access to system resources such as memory, CPUs (or groups of CPUs),networking, I/O, or the scheduler.

Updates to Control Groups in Red Hat Enterprise Linux 6.1 include:

• Added control group ability to throttle block device I/O to a particular device, either bytes per secondor Input/Output Operations Per Second (IOPS)

• Allow the creation of Hierarchical block device control groups, providing the ability to easily integratewith libvirt and other userspace

• The new block device control group tunable group_idle, providing better throughput with controlgroups while maintaining fairness

• The new autogroup feature to reduce latencies, for more interactive tasks during CPU intensiveworkloads

• the new cgsnapshot tool provides the ability to take a snapshot of the current control groupconfiguration

Note

Control Groups and other resource management features are discussed in detail in the Red HatEnterprise Linux 6 Resource Management Guide2

2.1. SchedulerA process (or task) scheduler is a specific kernel subsystem that is responsible for assigning the orderin which processes are sent to the CPU.

Scheduler updates include:

• optimize CPU scheduling algorithms by making better decisions on which CPU's processes shouldrun on based on the system NUMA topology

• fix undesirable side effects of tickless timer

• several optimizations that prevents load balancing from occuring too often.

• more use of RCU locking in the scheduler for better concurrent processing.

2 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Resource_Management_Guide/index.html

Performance updates and improvements

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• and many more optimizations and improvements

2.2. Performance updates and improvements• Numerous updates and improvements to VM and Transparent Huge Page support

• Perf_event updates, and add perf lock feature for better way to analyze lock events

• Add ftrace events, such as wakeup latency tracer, to graph tracer: more insight into maximumlatency for a task to get scheduled after wakeup, and trace of functions called during that time

• Introduce kprobes jump optimization to reduce overhead and enhance SystemTap performance

• i7300_edac, i7core_edac update supports monitoring of memory errors on motherboards using intel7300 chipset

2.3. Networking updates• Receive Packet Steering (RPS) breaks the bottleneck of having to receive network traffic for a NIC

on one CPU

• Receive Flow Steering (RFS) allows the optimal CPU to receive network data intended for a specificapplication

• Add getsockopt support for TCP thin-streams to reduce latency from retransmission of lost packetsin time-sensitive applications

• Add Transparent Proxy (TProxy) support for non-locally bound IPv4 TCP and UDP sockets (similarto Linux 2.2)

2.4. kdumpkdump is an advanced crash dumping mechanism. When enabled, the system is booted from thecontext of another kernel. This second kernel reserves a small amount of memory, and its onlypurpose is to capture the core dump image in case the system crashes.

In Red Hat Enterprise Linux 6.1 introduces the kernel message dumper, which is called when a kernelpanic occurs. The kernel message dumper provides easier crash analysis and allows 3rd party kernelmessage logging to alternative targets.

Additionally, the crashkernel=auto parameter syntax is removed. The default parameter syntax isnow crashkernel=:[@offset].

3. Desktop

Graphics HardwareRed Hat Enterprise Linux 6.1 Beta provides a range of updates for graphics hardware, most notably:

• The new driver for Intel Generation 6 Graphics integrated into the Sandy Bridge processor providesfull accelerated 2D and 3D graphics

• Added support for the Matrox MGA-G200ER graphics chipset

• An increased default resolution (1024 x 768 pixels) on monitors that do not supply Extended DisplayIdentification Data (EDID)

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Network ManagerNetworkManager is the desktop tool that is used to set up, configure and manage a wide range ofnetwork connection types. In Red Hat Enterprise Linux 6.1, NetworkManager has improved support forthe configuration of Wi-Fi Protected Access (WPA) Enterprise and Internet Protocol version 6 (IPv6).

4. Storage

LVM Snapshots of MirrorsThe LVM snapshot feature provides the ability to create backup images of a logical volume at aparticular 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 asit was prior to the change so that it can reconstruct the state of the device. In Red Hat Enterprise Linux6.1 the ability to take a snapshot of a mirrored logical volume is a fully supported feature.

LVM Stripe of MirrorsIt 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 thenumber 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 managementof identity and authentication. Centralizing identity and authentication services enables local cachingof 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 DirectoryServer, Active Directory, OpenLDAP, 389, Kerberos and LDAP. SSSD in Red Hat Enterprise Linux 6.1Beta is updated to version 1.5, providing the following bug fixes and enhancements:

• netgroups support

• 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

• Password obfuscation for LDAP account

Security

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Further Reading

The Deployment Guide3 contains a section that describes how to install and configure SSSD.

IPARed Hat Enterprise Linux 6.1 Beta features IPA as a Technology Preview. IPA is an integrated securityinformation management solution which combines Red Hat Enterprise Linux, Red Hat DirectoryServer, MIT Kerberos, and NTP. It provides web browser and command-line interfaces, and itsnumerous administration tools allow an administrator to quickly install, set up, and administer one ormore servers for centralized authentication and identity management.

SambaSamba is an open source implementation of the Common Internet File System (CIFS) protocol. Itallows 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 6.1Beta is updated to version 3.5.6.

Samba in Red Hat Enterprise Linux 6.1 Beta allows users to use their own Kerberos credentials whenaccessing CIFS mount, rather than needing same mount credentials for all access to the mount.

FreeRADIUSFreeRADIUS is an Internet authentication daemon, which implements the RADIUS protocol, asdefined in RFC 2865 (and others). It allows Network Access Servers (NAS boxes) to performauthentication for dial-up users. FreeRADIUS in Red Hat Enterprise Linux 6.1 Beta is updated toversion 2.1.10.

KerberosKerberos is a networked authentication system which allows users and computers to authenticateto each other with the help of a trusted third party, the KDC. In Red Hat Enterprise Linux 6.1 Beta,Kerberos (supplied by the krb5 package) is updated to version 1.9.

6. Security

OpenSCAPOpenSCAP 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). OpenSCAPsupports the SCAP components:• Common Vulnerabilities and Exposures (CVE)

• Common Platform Enumeration (CPE)

• Common Configuration Enumeration (CCE)

• Common Vulnerability Scoring System (CVSS)

3 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/chap-SSSD_User_Guide-Introduction.html

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• Open Vulnerability and Assessment Language (OVAL)

• Extensible Configuration Checklist Description Format (XCCDF)

Additionally, the openSCAP package includes an application to generate SCAP reports about systemconfiguration. openSCAP is now a fully supported package in Red Hat Enterprise Linux 6.1.

Smartcard support for SPICEThe Simple Protocol for Independent Computing Environments (SPICE) is a remote display protocoldesigned for virtual environments. SPICE users can view a virtualized desktop or server from the localsystem or any system with network access to the server. Red Hat Enterprise Linux 6.1 introducessupport for smartcard passthough via the SPICE protocol.

Further Reading

The Security Guide4 assists users and administrators in learning the processes and practices ofsecuring workstations and servers against local and remote intrusion, exploitation and maliciousactivity.

7. InstallationInstallation and boot support is added in Red Hat Enterprise Linux 6.1 Beta for the Emulex 10GbEPCI-E Gen2 and Chelsio T4 10GbE network adapters. Additionally, teh GRUB bootloaded is updatedwith support for booting volumes with a 4KB sector size on UEFI systems.

The installer in Red Hat Enterprise Linux 6.1 Beta will detect unsupported hardware platforms andprovide 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 adaptersRed Hat Enterprise Linux 6.1 Beta features improved support for iSCSI adapters at installation andboot time, including the ability to separate login credentials for iSCSI storage during installation andsupport for partial offload iSCSI adapters (e.g. the Emulex Tiger Shark adapter).

Red Hat Enterprise Linux 6 supports installation over iSCSI using auto-detection of BIOS iSCSIsettings 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 dynamicallyconfigured from iBFT settings during boot time.

4 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Security_Guide/

Compiler and Tools

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8. Compiler and Tools

8.1. SystemTapSystemTap is a tracing and probing tool that allows users to study and monitor the activities of theoperating system (particularly, the kernel) in fine detail. It provides information similar to the output oftools like netstat, ps, top, and iostat; however, SystemTap is designed to provide more filtering andanalysis options for collected information.

SystemTap in Red Hat Enterprise Linux 6.1 Beta is updated to version 1.4, providing:

• Alpha version of remote host scripting with --remote USER@HOST

• Optimization of near zero cost for dormant user probe points

Refer to the SystemTap Release Notes5 for more information.

8.2. 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 Beta is updated to version 7.2, providing many bugfixes andenhancements, including enhancements to the python scripting features, and C++ debuggingenhancements.

8.3. OProfileOProfile is a system-wide profiler for Linux systems. The profiling runs transparently in the backgroundand profile data can be collected at any time. In Red Hat Enterprise Linux 6.1 Beta, OProfile isupdated to version 0.9.6-12, providing support for AMD family 12h/14h/15h processors and IntelWestmere specific events.

8.4. ValgrindValgrind is an instrumentation framework for building dynamic analysis tools that can be used toprofile applications in detail. Valgrind tools are generally used to automatically detect many memorymanagement and threading problems. The Valgrind suite also includes tools that allow you to buildnew profiling tools to suit your needs.

Red Hat Enterprise Linux 6.1 Beta provides Valgrind version 3.6.0.

8.5. GNU Compiler Collection (GCC)The GNU Compiler Collection (GCC) includes, among others, C, C++, and Java GNU compilers andrelated support libraries. Red Hat Enterprise Linux 6 features version 4.4 of GCC, which includes thefollowing features and enhancements:• IBM z196 new instruction support and optimizations

• IBM z10 prefetch instruction support and optimizations

5 http://sourceware.org/ml/systemtap/2011-q1/msg00036.html

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8.6. libdfpThe libdfp library is updated in Red Hat Enterprise Linux 6.1 Beta. libdfp is a decimal floating pointmath library, and is available as an alternative to the glibc math functions on Power and s390xarchitectures, and is available in the supplementary channels.

8.7. EclipseEclipse is a powerful development environment that provides tools for each phase of the developmentprocess. It is integrated into a single, fully configurable user interface for ease of use, featuring apluggable architecture which allows for extension in a variety of ways.

An updated version of the Eclipse development environment is available in Red Hat Enterprise Linux6.1 Beta, providing the following updates and enhancements:

• All the major plugins are refreshed, including Valgrind and OProfile integration and the tools forworking 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

8.8. IcedTeaNew IcedTea Web Open Source Web Browser Plugin and Webstart implementation for OpenJDK.

• Allows browsers such as Firefox to load Java applets embedded in a web page

• Provides framework to launch JNLP (Java Network Launching Protocol) files

9. ClusteringClusters are multiple computers (nodes) working in concert to increase reliability, scalability, andavailability to critical production services. High Availability using Red Hat Enterprise Linux 6 can bedeployed in a variety of configurations to suit varying needs for performance, high-availability, loadbalancing, and file sharing.

The following major updates to clustering are available in Red Hat Enterprise Linux 6.1 Beta

• The cluster resource agent for the Network File System version 4 (NFSv4) resource agent now hasNFSv4 recovery support

• Rgmanager now supports the concept of critical and non-critical resources

• A restart recovery can now be performed without the need to relocate a service if restart fails

• System Administrators can now configure and run a cluster using command line tools. This featureprovides an alternative to manually editing the cluster.conf configuration file or using the graphicalconfiguration tools (Luci and Ricci)

• Red Hat Enterprise Linux High Availability on Red Hat Enterprise Linux KVM hosts is fully supported

• Comprehensive SNMP Trap support from all cluster daemons and sub-parts

• Additional watchdog integration allows a node to reboot itself when it loses quorum or is fencedusing fence_scsi

Virtualization

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Further Reading

The Cluster Suite Overview6 document provides an overview of Red Hat Cluster Suite for RedHat Enterprise Linux 6. Additionally, the High Availability Administration7 document describes theconfiguration and management of Red Hat cluster systems for Red Hat Enterprise Linux 6.

10. Virtualization

vhostThe new host kernel networking backend, vhost, is a fully supported feature in Red Hat EnterpriseLinux 6.1. vhost provides superior throughput and latency over the userspace implementation.

qcow2The qcow2 image format now supports caching of metadata. Additionally, support is added for livesnapshots using external qcow2 images.

Block I/O latency improvementsioeventfd 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 scansubpages inside hugepages and split them when merging is possible.

Additionally, KSM enablement can now be controlled on a per-VM basis.

PCI device assignment improvementsPCI configuration space access is improved, enabling a broader set of PCI devices to be device-assigned to guest VMs.

KVMClock ImprovementsIn Red Hat Enterprise Linux 6.1, the Time Stamp Counter (TSC) synchronization can now beautomatically detected on guest bootup or when a host CPU is hot-plugged. Additionally, the TSCsynchronization frequency is adjusted after a live migration.

QEMU monitorHuman Monitor pass through is enabled. Additionally, the new drive_del command allows libvirt tosafely remove a block device from a guest.

6 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Cluster_Suite_Overview/index.html7 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Cluster_Administration/index.html

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General Updates and Improvements• The maximum display resolution on qemu-kvm is now 2560x1600 pixels

• Red Hat Enterprise Linux 6.1 Beta includes the ability to expose an emulated Intel HDA sound cardto all guests. This update enables native sound support for many guests including the 64-bit versionof 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

• Stablity 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

11. Entitlement

Red Hat Subscription Manager and the Entitlements PlatformEffective software and infrastructure management requires a mechanism to handle the softwareinventory — both the type of products and the number of systems that the software is installed on. Inparallel with Red Hat Enterprise Linux 6.1, Red Hat is introducing a new Entitlement Platform whichprovides oversight for the software entitlements for an organization and a more effective contentdelivery system. On local systems, the new Red Hat Subscription Manager offers both GUI andcommand-line tools to manage the local system and its allocated subscriptions. A better methodto handle subscriptions will help our customers maintain their software compliance and will makeinstalling and updating Red Hat products much simpler.

Further Reading

The Red Hat Enterprise Linux 6.1 Beta Deployment Guide8 contains further information onmanaging subscriptions. Additionally, the Red Hat Enterprise Linux 6.1 Beta Installation Guide9

contains further information on the registration and subscription process at install time

12. General Updates

Automated Bug Reporting ToolRed Hat Enterprise Linux 6 introduced the new Automated Bug Reporting Tool (ABRT). ABRT logsdetails of software crashes on a local system, and provides interfaces (both graphical and commandline based) to report issues to Red Hat support. In Red Hat Enterprise Linux 6.1 Beta, ABRT isupdated to version 1.1.16. This update provides an enhanced graphical user interface (GUI) inaddition to a range of other bugfixes and enhancements.

8 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Deployment_Guide/index.html9 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Installation_Guide/index.html

Technology Previews

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openCryptokiopenCryptoki contains version 2.11 of the PKCS#11 API, implemented for IBM Cryptocards.openCryptoki is updated in Red Hat Enterprise Linux 6.1 Beta, providing many bugfixes andenhancements, including better overall performance.

OpenLDAPOpenLDAP is an open source suite the Lightweight Directory Access Protocol (LDAP) applicationsand development tools. OpenLDAP in Red Hat Enterprise Linux 6.1 Beta is updated to version 2.4.23.This updated version of OpenLDAP utilizes Network Security Services (NSS) cryptographic libraries,replacing OpenSSL.

TigerVNCTigerVNC provides client and server software for Virtual Network Computing (VNC). VNC is aremote display system, allowing a user to view a computing desktop environment over a networkconnection.TigerVNC is updated to version 1.1.0, providing many bugfixes enhanced encryptionsupport.

tunedtuned is a system tuning daemon that monitors system components and dynamically tunes systemsettings. 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 Beta, the tuned tuningprofiles now include support for the s390x architectures.

A. Technology PreviewsOpen Multicast Ping (Omping)

Open Multicast Ping (Omping) is a tool to test the IP multicast functionality primarily in the localnetwork. This utility allows users to test multicast and assists in the diagnosing if an issues isin the network configuration or elsewhere (i.e. a bug). In Red Hat Enterprise Linux 6 omping isprovided as a Technology Preview.

MatahariMatahari provides a set of Application Programming Interfaces (APIs) for operating systemsmanagement for remote access over QMF/QPID. In Red Hat Enterprise Linux 6.1, Matahari isconsidered a Technology Preview feature.

System Information Gatherer and Reporter (SIGAR)The System Information Gatherer and Reporter (SIGAR) is a library and command-line toolfor accessing operating system and hardware level information across multiple platformsand programming languages. In Red Hat Enterprise Linux 6.1 Beta, SIGAR is considered aTechnology Preview package.

fsfreezeRed Hat Enterprise Linux 6 includes fsfreeze as a Technology Preview. fsfreeze is a newcommand that halts access to a filesystem on disk. fsfreeze is designed to be used with hardwareRAID devices, assisting in the creation of volume snapshots. Further details on fsfreeze are in thefsfreeze(8) man page.

DIF/DIX supportDIF/DIX, is a new addition to the SCSI Standard and a Technology Preview in Red Hat EnterpriseLinux 6. DIF/DIX increases the size of the commonly used 512-byte disk block from 512 to 520

6.1 Release Notes

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bytes, adding the Data Integrity Field (DIF). The DIF stores a checksum value for the data blockthat is calculated by the Host Bus Adapter (HBA) when a write occurs. The storage device thenconfirms the checksum on receive, and stores both the data and the checksum. Conversely, whena read occurs, the checksum can be checked by the storage device, and by the receiving HBA.

The DIF/DIX hardware checksum feature must only be used with applications that exclusivelyissue O_DIRECT I/O. These applications may use the raw block device, or the XFS file system inO_DIRECT mode. (XFS is the only filesystem that does not fall back to buffered IO when doingcertain allocation operations.) Only applications designed for use with O_DIRECT I/O and DIF/DIX hardware should enable this feature. Red Hat Enterprise Linux 6 includes the Emulex LPFCdriver version 8.3.5.17, introducing support for DIF/DIX. For more information, refer to the StorageAdministration Guide6

Filesystem in UserspaceFilesystem in Userspace (FUSE) allows for custom filesystems to be developed and run in user-space.

btrfsBtrfs is under development as a file system capable of addressing and managing more files, largerfiles, and larger volumes than the ext2, ext3, and ext4 file systems. Btrfs is designed to make thefile system tolerant of errors, and to facilitate the detection and repair of errors when they occur. Ituses checksums to ensure the validity of data and metadata, and maintains snapshots of the filesystem that can be used for backup or repair. The btrfs Technology Preview is only available onthe x86_64 architecture.

Btrfs is still experimental

Red Hat Enterprise Linux 6 Beta includes Btrfs as a technology preview to allow you toexperiment with this file system. You should not choose Btrfs for partitions that will containvaluable data or that are essential for the operation of important systems.

LVM Application Programming Interface (API)Red Hat Enterprise Linux 6 Beta features the new LVM application programming interface (API) asa Technology Preview. This API is used to query and control certain aspects of LVM.

FS-CacheFS-Cache is a new feature in Red Hat Enterprise Linux 6 Beta that enables networked filesystems (e.g. NFS) to have a persistent cache of data on the client machine.

IPv6 support in IPVSThe IPv6 support in IPVS (IP Virtual server) is considered Technology Preview.

pacemakerPacemaker, a scalable high-availability cluster resource manager, is included in Red HatEnterprise Linux 6 as a Technology Preview. Pacemaker is not fully integrated with the Red Hatcluster stack.

XFS in the Red Hat Enterprise Linux 6 High Availability Add OnXFS in the Red Hat Enterprise Linux 6 High Availability Add On is considered Technology Preview.

6 http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html-single/Storage_Administration_Guide/index.html#id3654852

Technology Previews

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upd-unicast supportCluster membership can now be initiated using udp-unicast (UDPU). The older protocol (multicast)is often restricted by corporate IT policy, making it difficult to deploy clusters. Introducing UDPUsupport alliviates that limitation. This feature is considered a Technology Preview in Red HatEnterprise Linux 6.1.

certmongerThe certmonger service aims to manage certificates on behalf of services running on clientsystems. It warns administrators when a certificate which it has been asked to watch is nearingthe end of its validity period, and can be told to attempt to automatically obtain a new certificatewhen this happens. It supports certificates and private keys stored in either PEM or NSS databaseformats. It can interact with CAs running either IPA or certmaster, and is intended to be extensibleto support other implementations.

TPMTPM hardware can create, store and use RSA keys securely (without ever being exposed inmemory), verify a platform's software state using cryptographic hashes and more. The user spacelibraries, trousers and tpm-tools are considered a Technology Preview in this Red Hat EnterpriseLinux 6.

Brocade BFA DriverThe Brocade BFA driver is considered a Technology Preview feature in Red Hat Enterprise Linux6. The BFA driver supports Brocade FibreChannel and FCoE mass storage adapters.

SR-IOV on the be2net driverThe SR-IOV functionality of the Emulex be2net driver is considered a Technology Preview in RedHat Enterprise Linux 6.

Kernel Media support (Tech Preview)• Very current upstream video4linux

• Digital video broadcasting

• Primarily infrared remote control device support

• Many webcam support fixes and improvements

Remote Audit LoggingThe audit package contains the user space utilities for storing and searching the audit recordsgenerated by the audit subsystem in the Linux 2.6 kernel. Within the audispd-plugins subpackageis a utility that allows for the transmission of audit events to a remote aggregating machine. Thisremote audit logging application, audisp-remote, is considered a Technology Preview in Red HatEnterprise Linux 6.

Linux (NameSpace) Container [LXC]Linux (NameSpace) Containers [LXC] is a Technology Preview feature in Red Hat EnterpriseLinux 6 Beta that provides isolation of resources assigned to one or more processes. A process isassigned a separate user permission, networking, filesystem name space from its parent.

Error Detection And Correction (EDAC) driver interfaceThe Error Detection And Correction (EDAC) driver interface for processors based on the Intelmicroarchitecture codename Nehalem is considered a Technology Preview in this pre-releaseversion of Red Hat Enterprise Linux 6.

6.1 Release Notes

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B. Known Issues

B.1. Installer• In some circumstances, disks that contain a whole disk format (e.g. a LVM Physical Volume

populating a whole disk) are not cleared correctly using the clearpart --initlabel kickstartcommand. Adding the --all switch — as in clearpart --initlabel --all — ensures disksare cleared correctly.

• During the installation on POWER systems, the error messages similar to:

attempt to access beyond end of deviceloop0: rw=0, want=248626, limit=248624

may be returned to sys.log. The errors do not prevent installation and only occur during initialsetup. The filesystem created by the installer will function correctly.

• When installing on the s390x architecture, if the installation is being performed over SSH, avoidresizing the terminal window containing the SSH session. If the terminal window is resized duringinstallation, the installer will exit and installation will terminate.

• The kernel image provided on the CD/DVD is too large for Open Firmware. Consequently, on thePOWER architecture, directly booting the kernel image over a network from the CD/DVD is notpossible. Instead, use yaboot to boot from a network.

• The anaconda partition editing interface includes a button labeled Resize. This feature is intendedfor users wishing to shrink an existing filesystem and underlying volume to make room forinstallation of the new system. Users performing manual partitioning cannot use the Resize button tochange sizes of partitions as they create them. If you determine a partition needs to be larger thanyou initially created it, you must delete the first one in the partitioning editor and create a new onewith the larger size.

• Channel IDs(read, write, data) for network devices are required for defining and configuring networkdevices on s390 systems. However, system-config-kickstart — the graphical user interface forgenerating a kickstart configuration — cannot define channel IDs for a network device. To workaround this issue, manually edit the kickstart configuration that system-config-kickstart generatesto include the desired network devices.

B.2. Deployment• Some HP Proliant servers may report incorrect CPU frequency values in /proc/cpuinfo or /sys/

device/system/cpu/*/cpufreq. This is due to the firmware manipulating the CPU frequency withoutproviding any notification to the operating system. To avoid this ensure that the "HP PowerRegulator" option in the BIOS is set to "OS Control". An alternative available on more recentsystems is to set "Collaborative Power Control" to "Enabled".

B.3. Virtualization• Under some circumstances, installation of a Red Hat Enterprise Linux 6 virtual guest stalls after the

optional testing of media. Note that this issue has only been observed with Red Hat Enterprise Linux6 guests that utilize multiple virtualized CPUs. To work around this issue, use a media source that isknown to be verified, and skip the media test, or use a single virtualized CPU during installation.

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• In earlier versions of Red Hat Enterprise Linux, libvirt permitted PCI devices to be insecurelyassigned to guests. In Red Hat Enterprise Linux 6, assignment of insecure devices is disabled bydefault by libvirt. However, this may cause assignment of previously working devices to start failing.To enable the old, insecure setting, edit /etc/libvirt/qemu.conf, set "relaxed_acs_check = 1", andrestart libvirtd. Note that this action will re-open possible security issues.

• The balloon service on Windows 7 guests can only be started by the "Administrator" user.

• Libvirt uses transient iptables rules for managing NAT or bridging to virtual machine guests. Anyexternal command that reloads iptables state ( such as running system-config-firewall) will overwritethe entries needed by libvirt. Consequently, after running any command or tool that changes thestate of iptables, guests may lose access the network. To work around this issue, use the command'service libvirt reload' to restore libvirt's additional iptables rules.

• KVM users with a mix of virtio and ata disks should verify the boot device that anaconda choosesduring installation. To verify the boot device, locate the "Install Target Devices" list in the diskselection screen that follows the partitioning type screen. Verify the boot device selection, which isindicated by a selector in the left-most column of the "Install Target Devices" list.

• A Windows virtual machine must be restarted after the installation of the kernel windows driverframework. If the virtual machine is not restarted it may crash when a memory balloon operation isperformed.

• A dual function, 82576 interface (codename: Kawela, PCI Vendor/Device ID: 8086:10c9) cannothave both physical functions (PF's) device-assigned to a Windows 2008 guest. Either physicalfunction can be device assigned to a Windows 2008 guest (PCI function 0 or function 1), but notboth.

• virt-v2v is able to convert guests running on ESX server. A current limitation in virt-v2v means thatif an ESX guest has a disk with a snapshot, the snapshot must be on the same datastore as theunderlying disk storage. If the snapshot and underlying storage are on different datastores, virt-v2vwill report a 404 error while trying to retrieve the storage.

B.4. Storage and Filesystems• The NFSv4 server in Red Hat Enterprise Linux 6 currently allows clients to mount using UDP and

advertises NFSv4 over UDP with rpcbind. However, this configuration is not supported by Red Hatand violates the RFC 3530 standard.

• If a device-mapper-multipath device is still open, but all of the attached paths have been lost, thedevice is unable to create a new table with no paths. Consequently, the following unusual outputmay be returned from the multipath -ll output command:

mpatha (3600a59a0000c2fd0003079284c122fec) dm-0,size=2.0G hwhandler='0'|-+- policy='round-robin 0' prio=0 status=enabled| `- #:#:#:# - #:# failed faulty running`-+- policy='round-robin 0' prio=0 status=enabled |- #:#:#:# - #:# failed faulty running `- #:#:#:# - #:# failed faulty running

Output of this type indicates that there are no paths to the device. The erroneous lines in the outputpreceded by the string #:#:#:# will be removed in a future release.

6.1 Release Notes

18

• dracut currently only supports one FiberChannel over Ethernet (FCoE) connection to be used toboot from the root device. Consequently, booting from a root device that spans multiple FCoEdevices (e.g. using RAID, LVM or similar techniques) is not possible.

B.5. Networking• When configuring a network interface manually, including static IP addresses and search domains, it

is possible that a search entry will not be propagated to /etc/resolv.conf. Consequently, shorthost names that do not include the domain name will fail to resolve. To workaround this issue, add asearch entry manually to /etc/resolv.conf.

B.6. Clustering• luci will not function with Red Hat Enterprise Linux 5 clusters unless each cluster node has ricci

version 0.12.2-14

B.7. Authentication• none

B.8. Devices• Red Hat Enterprise Linux 6 only has support for the first revision of the UPEK Touchstrip fingerprint

reader (USB ID 147e:2016). Attempting to use a second revision device may cause the fingerprintreader daemon to crash. The command

lsusb -v -d 147e:2016 | grep bcdDevice

will return the version of the device being used in an individual machine.

• The Emulex Fibre Channel/Fibre Channel-over-Ethernet (FCoE) driver in Red Hat Enterprise Linux6 does not support DH-CHAP authentication. DH-CHAP authentication provides secure accessbetween hosts and mass storage in Fibre-Channel and FCoE SANs in compliance with the FC-SPspecification. Note, however that the Emulex driver (lpfc) does support DH-CHAP authenticationon Red Hat Enterprise Linux 5, from version 5.4. Future Red Hat Enterprise Linux 6 releases mayinclude DH-CHAP authentication.

• The recommended minimum HBA firmware revision for use with the mpt2sas driver is "Phase5 firmware" (i.e. with version number in the form 05.xx.xx.xx.) Note that following thisrecommendation is especially important on complex SAS configurations involving multiple SASexpanders.

B.9. Kernel• Loading the megaraid_sas driver on the kdump kernel will result in the insmod command being

blocked, returning messages similar to:

INFO: task insmod:201 blocked for more than 120 seconds.

Refer to BZ#68211024 for more information.

• In Red Hat Enterprise Linux 6.1, the nmi_watchdog registers with the perf subsystem.Consequently, during boot, the perf subsystem grabs control of the performance counter registers,

Desktop

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blocking oprofile from working. To resolve this, either boot with the nmi_watchdog=0 kernelparameter set, or run echo 0 > /proc/sys/kernel/nmi_watchdog to disable at run time. Tore-enable the watchdog, use the command echo 1 > /proc/sys/kernel/nmi_watchdog.

• Due to the way ftrace works when modifying the code during startup, the NMI watchdog causes toomuch noise and ftrace can not find a quiet period to instrument the code. Consequently, machineswith more than 512 cpus will encounter issues with the NMI watchdog. Such issues will return errormessages similar to "BUG: NMI Watchdog detected LOCKUP" and have either 'ftrace_modify_code'or 'ipi_handler' in the backtrace. To work around this issue, disable nmi_watchdog using thecommand:

nmi_watchdog=0

• Creating many 'cpu' control groups (cgroups) on a system with a large number of CPUs will slowdown the machine when the control groups feature is enabled. To work around this issue, disablecontrol groups.

• On 64-bit POWER systems the EHEA NIC driver will fail when attempting to dump a vmcore viaNFS. To work around this issue, utilize other kdump facilities, for example dumping to the localfilesystem, or dumping over SSH.

• A BIOS emulated floppy disk might cause the installation or kernel boot process to hang. To avoidthis, disable emulated floppy disk support in the BIOS.

• The preferred method to enable nmi_watchdog on 32-bit x86 systems is to use eithernmi_watchdog=2 or nmi_watchdog=lapic parameters. The parameter nmi_watchdog=1 isnot supported.

• The kernel parameter, pci=noioapicquirk, is required when installing the 32 bit variant of RedHat Enterprise Linux 6 on HP xw9300 workstations. Note that the parameter change is not requiredwhen installing the 64 bit variant.

B.10. Desktop• When enabled, fingerprint authentication is the default authentication method to unlock a

workstation, even if the fingerprint reader device is not accessible. However, after a 30 second wait,password authentication will become available.

• Evolution's IMAP backend only refreshes folder contents under the following circumstances: whenthe user switches into or out of a folder, when the auto-refresh period expires, or when the usermanually refreshes a folder (i.e. using the menu item Folder > Refresh). Consequently, whenreplying to a message in the Sent folder, the new message does not immediately appear in the Sentfolder. To see the message, force a refresh using one of the methods describe above.

• The clock applet in the GNOME panel has a default location of Boston, USA. Additional locationsare added by via the applet's preferences dialog. Additionally, to change the default location, left-click the applet, hover over the desired location in the "Locations" section, and click the "Set..."button that appears.

• In some multi-monitor configurations (e.g. dual monitors with both rotated), the cursor confinementcode produces incorrect results. For example, the cursor may be permitted to disappear offscreenwhen it should not, or be prevented from entering some areas where it should be allowed to go.Currently, the only work around to this issue is to disable monitor rotation.

6.1 Release Notes

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• If a Russian keyboard is chosen during system installation, the login screen is configured to useRussian input for user names and passwords by default. However, pressing Left Shift and RightShift does not cause the input to change to ASCII mode. Consequently, the user cannot log in. Towork around this issue, run the following sequence, as root, post installation:

. /etc/sysconfig/keyboard; echo $LAYOUT | grep -q ",us" && gconftool-2--direct --config-source xml:readwrite:/var/lib/gdm/.gconf --set/apps/gdm/simple-greeter/recent-layouts --type list --list-type string $(echo$LAYOUT | awk -F, '{ print "[" $2 "," $1 "]"; }') && echo "DONE"

C. Revision HistoryRevision 1-0 Tue Mar 22 2011 Ryan Lerch rlerch@redhat.com

Initial Release of the Red Hat Enterprise Linux 6.1 Beta Release Notes