Eric Siebert’s recent post on optimizing the host environment is a very important concern that may frequently be passed aside in the interest of reducing implementation time for virtual environments. In this blog, I would like to pipe in with a few of my own tips related to the host environment. These strategies are applicable to many virtualization platforms, and will transcend products as virtualization advances.
DNS configuration for the hosts
Having a correct DNS environment is important for all systems, not just virtual environments. Pay particular order to the suffix search order, as the first result for queries should be consistent and timely across hosts. Also, consider host entries for fixed systems, with an entry for the host itself, all other hosts, the management system and any other relevant systems with which the host would need to communicate. A specific issue is VMware’s DRS functionality, which can have issues with incorrect DNS configurations.
Time configuration for the hosts
For platforms that are Windows based and members of an Active Directory domain, this concern is somewhat eased. But for Linux systems, you want to have an automated mechanism in place to manage accurate time across hosts. For ESX and VirtualCenter, Eric again has covered this well over on SearchVMware.com with a tip.
Also decide whether you want guest virtual machines to sync time with the host via the driver software (VMware Tools, Guest Additions, etc.) This will relieve issues that go with multiple time zone support as well as separate issues in time synchronization.
Get environment agent notifications right
For virtualization hosts on the server level, all hardware failure notifications should be configured to the fullest extent possible. This can be device alerts (Dell DRAC/HP iLO), SNMP alerts, agent configurations or even blade server management software. With the scope of the virtual environment, maybe even use multiple notification mechanisms.
Single hypervisor per platform
This is more relevant on desktop environments, but it goes without saying that you should not install two products on a single system. Even though it may be tempting to have the functionality of multiple platforms, it may complicate the host environment. Take VMware Server and Sun xVM VirtualBox as an example, they theoretically could exist on same systems because of the VMware Bridge protocol binding and the VirtualBox explicit host adapters able to have their own configuration. This is one of those just-because-you-can-does-not-mean-you-should scenarios.
Host configuration is an area ripe for configuration procedures and policy enforcement to ensure consistent behavior among host systems. The procedural investment can usually help present the virtualization solution with more credibility as well.