Make VirtualCenter highly available with VMware Virtual Infrastructure

November 17th, 2008 by jason Leave a reply »

A few days ago I posted some information on how to make VirtualCenter highly available with Microsoft Cluster Services.

Monday Night Football kickoff is coming up but I wanted follow up quickly with another option (as suggested by Lane Leverett): Deploy the VirtualCenter Management Server (VCMS) on a Windows VM hosted on a VMware Virtual Infrastructure cluster. Why is this a good option? Here are a few reasons:

  1. It’s fully supported by VMware.
  2. You probably already have a VI cluster in your environment you can leverage. Hit the ground running without spending the time to set up MSCS.
  3. Removing MSCS removes a 3rd party infrastructure complexity and dependency which requires an advanced skill set to support.
  4. Removing MSCS removes at least one Windows Server license cost and also removes the need for the more expensive Windows Enterprise Server licensing and the special hardware needs required by MSCS.
  5. Green factor: Let VCMS leverage the use of VMware Distributed Power Management (DPM).

How does it work? It’s pretty simple. A virtualized VCMS shares the same advantages any other VM inherently has when running on a VMware cluster:

  1. Resource balancing of the four food groups (vProcessor, vRAM, vDisk, and vNIC) through VMware Distributed Resource Scheduler (DRS) technology
  2. Maximum uptime and quick recovery via VMware High Availability (HA) in the event of a VI host failure or isolation condition (yes, HA will still work if the VCMS is down. HA is a VI host agent)
  3. Maximum uptime and quick recovery via VMware High Availability (HA) in the event of a VMware Tools heartbeat failure (ie. the guest OS croaks)
  4. Ability to perform host maintenance without downtime of the VCMS

A few things to watch out for (I’ve been there and done that, more than once):

  1. If you’re going to virtualize the VCMS, be sure you do so on a cluster with the necessary licensed options to support the benefits I outlined above (DRS, HA, etc.) This means VI Enterprise licensing is required (see the licensing/pricing chart on page 4 of this document). I don’t want to hide the fact that a premium is paid for VI Enterprise licensing, but as I pointed out above, if you’ve already paid for it, the bolt ons are unlimited use so get more use out of them.
  2. If your VCMS (and Update manager) database is located on the VCMS, be sure to size your virtual hardware appropriately. Don’t go overboard though. From a guest OS perspective, it’s easier to grant additional virtual resources from the four food groups than it is to retract them.
  3. If you have a power outage and your entire cluster goes down (and your VCMS along with it), it can be difficult to get things back on their feet while you don’t have the the use of the VCMS. Particularly if you’ve lost the use of other virtualized infrastructure components such as Microsoft Active Directory. Initially it’s going to be command line city so brush up on your CLI. It really all depends on how badly the situation is once you get the VI hosts back up. One example I ran into is host A wouldn’t come back up. Host B wasn’t the registered owner of the VM I needed to bring up. This requires running the vmware-cmd command to register the VM and bring it up on host B.

Well, I missed the first few minutes of Monday Night Football, but everyone who reads (tolerates) my ramblings is totally worth it.

Go forth and virtualize!

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6 comments

  1. Mike Foley says:

    I put my domain controller and VirtualCenter VM’s on a Windows host running VMware Server instead. The Windows host is not a member of a domain. I have a backup domain controller on the ESX datacenter.

    It all runs quite well and is relatively easy to back up.

    mike

  2. Roger Lund says:

    Jason,

    Great write up!

    I added a link on my blog.

    Thanks again.

    Roger

    http://rogerlunditblog.blogspot.com/

  3. andrewstaflin says:

    Did you hear about VMware FT? I just read a bit about it on http://www.virtualizationteam.com/virtualization-vmware/vmware-esx-40-ft-fault-tolerant-sneak-peek.html Would u think that would replace VMware HA? I had seen a video even of FT on that link. Is it available yet?

  4. jason says:

    Yes I’ve heard of FT and no I don’t think it’s designed to replace HA. Fault Tolerance (FT) (formerly known as continuous availability) is more of a hot online DR type solution whereas HA is a limited downtime solution where VMs are recovered in the same Datacenter.

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