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Thursday, May 26, 2016

Enabling/disabling "basic" repositories in RHEL

Default installation of Red Hat Enterprise Linux (using free RHEL Developer Subscription) has, IMHO, a rather strange choice of repositories configured by default. Enabling Optional and Supplementary repositories, along with EPEL would be first steps and we can also get rid of not used ones (we can always enable them later if needed).

Extra Packages for Enterprise Linux (EPEL)
# rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm


Red Hat Enterprise Linux 7 Server - Optional
# subscription-manager repos --enable=rhel-7-server-optional-rpms
# subscription-manager repos --enable=rhel-7-server-eus-optional-rpms


Red Hat Enterprise Linux 7 Server - Supplementary
# subscription-manager repos --enable=rhel-7-server-supplementary-rpms
# subscription-manager repos --enable=rhel-7-server-eus-supplementary-rpms


Red Hat Enterprise Linux for Real Time
# subscription-manager repos --disable=rhel-7-server-rt-rpms
# subscription-manager repos --disable=rhel-7-server-rt-beta-rpms


Red Hat Enterprise Linux High Availability
# subscription-manager repos --disable=rhel-ha-for-rhel-7-server-rpms
# subscription-manager repos --disable=rhel-ha-for-rhel-7-server-eus-rpms


Red Hat Enterprise Linux Resilient Storage
# subscription-manager repos --disable=rhel-rs-for-rhel-7-server-rpms
# subscription-manager repos --disable=rhel-rs-for-rhel-7-server-eus-rpms

Monday, May 9, 2016

Error while installing X2Go Server on Red Hat Enterprise Linux

Configuration:
Red Hat Enterprise Linux Server 7.2 (Maipo) base installation (Server with GUI) with EPEL enabled.

Issue:
Dependencies errors while trying to install X2Go server.

Error:

# yum install x2goserver
(...)
Error: Package: x2goserver-4.0.1.19-6.el7.x86_64 (epel)
           Requires: perl(Capture::Tiny)
Error: Package: x2goserver-4.0.1.19-6.el7.x86_64 (epel)
           Requires: perl(Config::Simple)
Error: Package: x2goserver-4.0.1.19-6.el7.x86_64 (epel)
           Requires: perl(File::Which)


Solution:
Required packages (perl-Capture-Tiny, perl-Config-Simple and perl-File-Which) are not provided by EPEL for EL7 but are available in "Red Hat Enterprise Linux 7 Server - Optional (RPMs)" repository that needs to be enabled.

yum-config-manager --enable rhel-7-server-optional-rpms

Friday, March 13, 2015

Live Migration fails due to CPU features incompatibility

Configuration:
Windows 2012 R2 on IBM System x3650 M3 (type 7945)

Problem:
You can migrate VMs started on certain hosts to all hosts in cluster but not back if the VM has been restarted on certain subset of hosts.

Error:
Live migration of "Virtual Machine VMNAME" failed.

Virtual machine migration operation for "VMNAME" failed at migration destination "HYPERVHOST". (Virtual machine ID XXX-XXX-XXXX)

The virtual machine "VMNAME" is using processor-specific features not supported on physical computer "HYPERVHOST". To allow for migration of this virtual machine to physical computers with different processors, modify the virtual machine settings to limit the processor features used by the virtual machine. (Virtual machine ID XXX-XXX-XXXX)


Reason:
AES capabilities are not available on some of the hosts. VMs started on hosts without AES enabled can be migrated around without any issues but VMs started on AES enabled hosts can be migrated only between other AES enabled hosts.


Solution:
Old versions of BIOS on these type of machines had AES disabled by default. There is no BIOS configuration switch to enable/disable it. To fix this BIOS needs to be flashed to version 1.10 or newer and then restored to default settings to enable AES.

Sources:
VMware VMotion fails with "CPU is incompatible" error - IBM Servers