E.5.2 Preparations for Servers

In addition to the operations in "Chapter 8 Defining and Configuring the Server Environment", the following operations are necessary.

Installation and configuration of the host OS
When installing a VM host on an L-Server, refer to "Appendix A Installing VM Hosts on Physical L-Servers" in the "Setup Guide CE".
Settings for /etc/sysconfig/libvirt-guests of the host OS
/etc/sysconfig/libvirt-guests is a definition file that is used to automatically stop guest OSs when their hypervisor is stopped.
If a hypervisor is stopped or restarted while its guest OSs are being operated, all virtual machines on the hypervisor will be suspended.
The suspension of the virtual machines is canceled when the hypervisor is started or restarted, and then suspended tasks are resumed.
Resuming tasks from the point of suspension may cause problems such contradictions in database transactions. In order to avoid this type of problem, the settings explained in this section are required.
Edit the /etc/sysconfig/libvirt-guests of the VM host as follows:
1. Cancel the commenting out of the #ON_BOOT=start line, and then change it to ON_BOOT=ignore.
2. Cancel the commenting out of the #ON_SHUTDOWN=suspend line, and then change it to ON_SHUTDOWN=shutdown.
3. Cancel the commenting out of the #SHUTDOWN_TIMEOUT=0 line, and then change it to SHUTDOWN_TIMEOUT=300.
  For the VM guest, set the time between when the shutdown command is sent from the VM host and the when the VM guest is actually powered off. The unit is seconds.
Settings for /etc/sysconfig/libvirtd of the host OS
1. Add the line containing "LANG=C".
2. Restart libvirtd.
Note
- Version check and upgrade of libvirt packages
  Check if the version of the libvirt package of the Host OS is 0.9.4-23.el6_2.4 or later.
  The libvirt package contains some security incompatibilities.
  If the package is an earlier version, upgrade it.
  For details, refer to the following web site.
  URL: https://access.redhat.com/knowledge/solutions/71283
- When using RHEL6.4 or later on a VM host, check if each of the following packages is the version listed below or a later one. If the package is an earlier version, upgrade it.
  - augeas-0.9.0-4.el6.x86_64.rpm
  - libvirt-0.10.2-18.el6_4.5.x86_64.rpm
  - libvirt-client-0.10.2-18.el6_4.5.x86_64.rpm
  - libvirt-debuginfo-0.10.2-18.el6_4.5.x86_64.rpm
  - libvirt-devel-0.10.2-18.el6_4.5.x86_64.rpm
  - libvirt-lock-sanlock-0.10.2-18.el6_4.5.x86_64.rpm
  - libvirt-python-0.10.2-18.el6_4.5.x86_64.rpm
  - sanlock-2.6-2.el6.x86_64.rpm
  - sanlock-lib-2.6-2.el6.x86_64.rpm
  There is a problem with libvirt. For details, refer to the following:
  URL: https://bugzilla.redhat.com/show_bug.cgi?id=953107
Configure SSH connection
Perform configuration to enable SSH connections from the admin server of Resource Orchestrator to the VM host using the admin LAN.
Configure the host name for the host OS
The host name is the character string output when the following command is executed on the host OS.
#hostname -s <RETURN>
Configure the host name of the host OS to be unique among all target host OSs managed by Resource Orchestrator.
Do not configure the same host names for multiple host OSs.

Prerequisites for L-Server Migration

Prerequisites for virtual L-Server live/cold migration in RHEL-KVM environments are described as follows:

The following items for the source and destination VM hosts for migration must be the same
- Kernel versions (including minor versions)
  These prerequisites are necessary for live migration.
- CPU architectures (Intel64 or x86)
- CPU model names
The disk used for a virtual L-Server must be connected to the destination VM host
The virtual bridge connected to a virtual L-Server must be in the destination VM host.

Configuration for L-Server Live Migration

When using Resource Orchestrator in RHEL-KVM environments, SSH is used for virtual L-Server live migration.

The following settings must be configured in each host that performs live migration of L-Servers, using the manager.

/etc/hosts configuration
configuration when using SSH

Refer to the following sections in the "Red Hat Enterprise Linux 6 Virtualization Administration Guide", and configure the settings.

Chapter 5. KVM live migration

Chapter 6. Remote management of guests

URL: http://docs.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Administration_Guide/index.html

Do not set the passphrase.
Specifically, do not enter the passphrase when executing the "ssh-keygen -t rsa" command to create an SSH key pair.
For details on passphrases, refer to the following:

URL: https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Administration_Guide/chap-Virtualization_Administration_Guide-Remote_management_of_virtualized_guests.html

The manuals for Red Hat Enterprise Linux can be referred to from the following URL.

URL: https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/index.html

Configuration of Swap Area for the Host OS

When there is insufficient swap area for the Host OS, the virtual L-Server may fail to start. Be sure to configure it appropriately.

For details, refer to the following section in the "Red Hat Enterprise Linux 6 Virtualization Administration Guide".

Chapter 7. Overcommitting with KVM

7.1. Introduction

URL:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Virtualization_Administration_Guide/chap-Virtualization-Tips_and_tricks-Overcommitting_with_KVM.html

When it is difficult to secure sufficient swap area, it is also possible to configure the kernel parameters (/proc/sys/vm/overcommit_memory) to avoid failure of start operations due to a lack of virtual L-Server memory space.

For details, refer to the following section in the "Red Hat Enterprise Linux 6 Performance Tuning Guide".

Chapter 5. Memory

5.4. Capacity Tuning

URL:
https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Performance_Tuning_Guide/s-memory-captun.html

Configuration for Red Hat DM Multipath

Edit the /etc/multipath.conf configuration file, and perform the following:

Set the user_friendly_names attribute to "yes".
Do not set the alias attribute.
Leave other settings at their default values.

For details, refer to the following RedHat document:

URL: https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/html/DM_Multipath/index.html

The manuals for Red Hat Enterprise Linux can be referred to from the following URL.

URL: https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/index.html