CentOS 6.9 Release Notes
Last updated: April 5, 2017
- Install Media and sha256sum
- Major changes
- Deprecated Features
- Known Issues
- Packages and Applications
- How to help and get help
- Further Reading
Translations of these release notes are available for the following languages :
Welcome to the CentOS 6.9 release. CentOS is an Enterprise-class Linux Distribution derived from sources freely provided to the public by Red Hat1. You can read our official product announcement for this release here
CentOS conforms fully with Red Hat's redistribution policy and aims to be functionally compatible. CentOS mainly changes packages to remove upstream vendor branding and artwork.
Similar to the practice of the upstream vendor, there is no supported path to 'upgrade' an installation of a prior major CentOS release (CentOS 5) to a new major release. This is not a CentOS imposed limitation, but rather reflects the upstream's approach on this matter. People who feel adventuresome and want to experiment are reminded to take and test backups first. As a note to people who attempt the upgrade in spite of this warning, such as by the unsupported upgradeany option from the media install command line, please note that you will need to manually retrieve the current centos-release package, manually do a rpm -e --nodeps removal of the prior centos-release package, and then manually install the CentOS 6 centos-release package, before yum can have any chance of working properly.
The Continuous Release (CR) repository makes generally available packages that will appear in the next point release of CentOS, on a testing and hotfix basis until formally released.
Please read through the other sections before trying an install or reporting an issue.
NOTE: There is NO mechanism to pick only partial upgrades of packages to CentOS-6.9. All packages and updates to the 6.9 tree are built against the 6.9 tree and may not work correctly with older 6.x packages. If you want some packages in 6.9, please upgrade all packages. You will have issues if you perform only partial updates.
3. Install Media and sha256sum
The installation kit is split into two DVDs. It is possible to do a full install with only the first DVD. The second DVD contains only supplementary RPMs, which can be installed afterwards if needed. The installer does not ask for the second DVD during installation. You should check the sha256sum of the downloaded installation images.
sha256sum x86_64: d27cf37a40509c17ad70f37bc743f038c1feba00476fe6b69682aa424c399ea6 CentOS-6.9-x86_64-bin-DVD1.iso 631b8640460f46a8139a6a7cbbac5f3594d08c32945449b6bbd65234929ce7a4 CentOS-6.9-x86_64-bin-DVD2.iso 422af57b493b8af49d485885a730c5a1d955f803fac85aa51311c393168b9080 CentOS-6.9-x86_64-minimal.iso 6b2cbec908708476389b143841a8e73462506de0744bda8b4192d3655d5bb8d2 CentOS-6.9-x86_64-netinstall.iso ae56f677786673ad476477ed2df84ce80cf5f9b90a44e25146e69ef3cfd02602 CentOS-6.9-x86_64-LiveDVD.iso sha256sum i386: 0724a468ec0c4ac46ac6a1daba0273be697a37bb7f4e9fed8ad84ad270cdee2f CentOS-6.9-i386-bin-DVD1.iso d95e427ca39588f4287f3bfdb080110c8dcbbfff76e1a6394395ec06858c8275 CentOS-6.9-i386-bin-DVD2.iso e104b3bc2261e40c020e4047d31a4454a00435787c54fb0a376261f9348382b7 CentOS-6.9-i386-minimal.iso c498a47b5ec47ecc8423c96bb80e5dd530e4d98bb839c60476cf113d1e4de0d6 CentOS-6.9-i386-netinstall.iso 4f7cd0be1c223b22427830b101e3e1765a93d27ed668047d8183976247a8a427 CentOS-6.9-i386-LiveDVD.iso
ISO downloads are available here
4. Major changes
- Due to size constraints of CDs, there is no longer a LiveCD. Keeping the size small enough would have required removing everything that makes a GUI desktop functional. The LiveDVD can be copied to a USB key and used if required.
- GnuTLS now supports TLS v1.2. All packages in CentOS utilizing cryptography now support TLS v1.2.
- postfix, vsftpd, rsyslog7, ipa-server, 389-ds-base, krb5-server, sssd and libvirt have improved functionality for selecting which cipher suites are allowed.
Net::SSLeay and IO::Socket:SSL Perl modules have been improved for better TLS support.
- Support for insecure cryptographic protocols and algorithms has been dropped. This affects usage of MD5, SHA0, RC4 and DH parameters shorter than 1024 bits.
- cloud-init, a tool for configuring new cloud instances, has now been added. Please see the entry on cloud-init in the "Known issues" section below.
- pacemaker now supports alert agents, allowing more flexibility in reacting to events in the cluster.
- clufter, a tool for converting and analyzing cluster configuration files, has been rebased to version 0.59.8.
- ca-certificates has been updated to include the latest certificate authorities as provided by the Mozilla Foundation.
- A new package cpuid is now available for displaying information about the CPUs in the system.
- Setting NO_DHCP_HOSTNAME in /etc/sysconfig/network to true will prevent network initialization scripts from changing the hostname.
If you don't want to let NetworkManager update your /etc/resolv.conf, you can now add dns=none to /etc/NetworkManager/NetworkManager.conf to achieve this.
- A new smartPQI driver for Microsemi storage adapters is now available.
- mpt3sas and megaraid_sas storage drivers have been updated to support more devices.
- guest-set-user-password allows setting the password for any user in a QEMU/KVM virtual machine.
5. Deprecated Features
The following device drivers have been deprecated, they may be removed in future releases and will not receive updates:
The following controllers from the megaraid_sas driver have been deprecated:
- Dell PERC5, PCI ID 0x15
- SAS1078R, PCI ID 0x60
- SAS1078DE, PCI ID 0x7C
- SAS1064R, PCI ID 0x411
- VERDE_ZCR, PCI ID 0x413
- SAS1078GEN2, PCI ID 0x78
The following controllers from the be2iscsi driver have been deprecated:
- BE_DEVICE_ID1, PCI ID 0x212
- OC_DEVICE_ID1, PCI ID 0x702
- OC_DEVICE_ID2, PCI ID 0x703
NOTE: Deprecated drivers SHOULD still function in CentOS 6 until EOL, they will likely not be supported in future versions of CentOS (ie, CentOS 7)
The following packages have been deprecated and may be removed in future releases of CentOS 6. They will no longer receive updates:
The following items have seen some or all items removed from the upstream source code:
- openswan component
- seabios component
- Btrfs file system
- eCryptfs file system
- mingw component
- virtio-win component
- fence-agents component
- systemtap component
- matahari component
- openscap component
Please see the Red Hat Technical Notes for more details concerning deprecated and removed functionality. Please pay special attention to information about using MD5, MD4 and SHA0 in cryptography packages and new limitations in accepted Diffie-Hellmann (DH) parameters.
6. Known Issues
- On UEFI-capable systems, CentOS 6.x writes its boot configuration to /boot/efi/EFI/redhat. This will cause problems for those who want to have CentOS and RHEL installed on the same system. This issue may remain unfixed for the lifetime of CentOS 6. CentOS 7 does not have this issue.
UEFI on CentOS-6.9: None of the i386 (32 bit) CentOS-6.9 ISOs will work with UEFI. All the x86_64 CentOS-6.9 ISOs (except LiveDVD) should boot and work with UEFI. No versions of CentOS 6 will work with Secure Boot turned on. Secure Boot must be disabled to install CentOS 6. (For further detail please take a look at CentOS Bug #6321).
The initscripts package has a bug preventing GRE and IPIP interfaces from starting at bootup. If you have such interfaces, please update with yum update --exclude initscripts to keep using the old initscripts package until a fix has been released.
A bug fix to glibc will probably be released shortly. If you want to avoid booting first for the 6.9 kernel and then shortly afterwards for the new glibc, you may want to wait until the updated glibc has been released.
Even though there is an option for upgrading when booting from the .iso images, the recommended way of upgrading is via yum update. Minimal will only update the packages that reside on the minimal iso, and when booting from DVD, the installer can't handle switching to the 2nd DVD if upgrading a package that resides on the 2nd DVD.
A new cloud-init package is now included in CentOS 6.9. The package has been rebuilt without changes from the upstream cloud-init. Installing cloud-init changes PasswordAuthentication in /etc/ssh/sshd_config to no. While that setting is generally recommended for security, it may cause problems for those users who expect the initial configuration to allow ssh'ing in with a password. In addition, an unconfigured cloud-init installation may cause delays up to 5 minutes when booting. When configured properly, the startup delays will be eliminated. If you don't know for sure you need the cloud-init package, it is advised to not install it. The package gets installed only if you explicitly select it from the optional packages, it is not installed by default. As with CentOS 6.8, there is an alternative CentOS-tailored cloud-init in the extras repository. The cloud-init in extras is probably a better fit for most users.
On Intel and AMD based processor architectures, CentOS 6 requires PAE support for 32-bit x86 chips, following the upstream's requirement
- The installer needs at least 406MB of memory to work. Text mode will automatically be used if the system has less than 632MB of memory.
The text installer has limited capabilities compared to the GUI installer. Most notably there is no support for configuring partition layout, storage methods or package selection. Please refer to the official documentation for details. Here you can find some useful information on creating and using kickstart files which can be used to perform advanced configuring without the need for the GUI installer.
- The message "Insufficient memory to configure kdump!" appears during install. This is a known issue which appears on systems with less than 2 GB RAM. This can be ignored.
- Make sure that you setup correctly the selinux context of the public key if you transfer it to a CentOS 6 server with selinux enabled. Otherwise selinux might forbid access to the ~/.ssh/authorized_keys file and by matter of consequence key authentication will not work. In order to setup the correct context you can use:
restorecon -R -v /home/$ACCOUNT/.sshssh-copy-id from CentOS 6 is aware of selinux contexts and the previous workaround is not needed.
Many people have complained that Ethernet interfaces are not started with the new default NetworkManager tool. See CentOS-6 FAQ#2.
Several packages have .centos. in their name but are not modified packages, see CentOS Bug #5281 for details. Here are the SRPMS still affected in the 6.9:
There is an issue with loading the ipv6 kernel module in some cases, which produces this error: Unknown symbol unregister_inet6addr_notifier . See bug 10927 for details.
Due to the changes in the Xorg subsystem the VirtualBox Tools have to be rebuilt for the GUI to start
If you use the SCL or Xen4CentOS repositories the locations of these have changed as these repos are now being maintained by Special Interest Groups. If you get errors updating your SCLs, do: yum remove centos-release-SCL then yum install centos-release-scl-rh. Xen should update as part of the normal update process.
One can do USB key installs by using dd to copy individual ISO files to a USB key using the device name (not the partition name). This will overwrite the entire USB key. Here is an example for the DVD1:
dd if=CentOS-6.9-x86_64-bin-DVD1.iso of=/dev/sdb
7. Packages and Applications
7.1. Packages modified by CentOS
7.2. Packages removed from CentOS that are included upstream
7.3. Packages added by CentOS that are not included upstream
7.4. Packages released as 6.8 updates with older packages on the 6.9 install media
All CentOS sources are now hosted at vault.centos.org:
Software Collections: http://vault.centos.org/6.9/SCL/Source/SPackages/
9. How to help and get help
As a CentOS user there are various ways you can help out with the CentOS community. Take a look at our Contribute page for further information on how to get involved.
9.1. Special Interest Groups
CentOS consists of different Special Interest Groups (SIGs) that bring together people with similar interests. The following SIGs already exist:
Artwork - create and improve artwork for CentOS releases and promotion
Promotion - help promoting CentOS online or at events
Virtualization - unite people around virtualization in CentOS
And we encourage people to join any of these SIGs or start up a new SIG, e.g.
- Alpha, S390, Sparc and PPC port - help with porting CentOS to other architectures
- Hardware compatibility - provide feedback about specific hardware
- RPM Packaging - contribute new useful RPM packages
- Translation - help translating the documentation, website and Wiki content
9.2. Mailinglists and Fora
9.3. Wiki and Website
Even as an inexperienced CentOS user we can use your help. Because we like to know what problems you encountered, if you had problems finding specific information, how you would improve documentation so it becomes more accessible. This kind of feedback is as valuable to others as it would have been to you so your involvement is required to make CentOS better.
So if you want to help out and improve our documentation and Wiki, register on the Wiki or subscribe to the centos-docs mailing list.
10. Further Reading
The following websites contain large amounts of information to help people with their CentOS systems :
Upstream release notes and documentation : https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/6.9_Release_Notes/index.html
Upstream technical notes : https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/6.9_Technical_Notes/index.html
We thank everyone involved for helping us produce this product and would like to specifically acknowledge the extra effort made by the QA Team. Without them working almost 24/7 we couldn't have released this as fast as we did.
Copyright (C) 2017 The CentOS Project