VM /ETC

Posts Tagged ‘highavailability’

So, who wants free VMware High Availability? That’s the title of a post created by Leo Raikhman on his Leo’s Ramblings blog. In this post, Leo has published the steps and scripting necessary to simulate VMware’s VI3 High Availability (HA) feature. Leo’s script works without VirtualCenter (VC), so VMware customer’s who have not implemented VC can manually create “HA -like” awareness between 2 ESX hosts. If one of the ESX servers goes offline then the virtual machines (VMs) are auto restarted on the other host. Of course, the VMs must be created on shared storage for this to work.

Before considering this script as a replacement understand the major differences between VirtualCenter HA and Leo’s HA:

• Leo’s script only works between 2 ESX hosts while VC HA can be configured with up to 32 ESX hosts as of VI 3.5 (actually using 32 host HA clusters is another topic, but it can be done)
• Leo’s script needs the ESX Service Console as written. It would need to be ported for the RCLI to work with ESXi. VC HA works with both ESX and ESXi
• VC provides a visual status for the health of your HA cluster via the VI Client
• VC HA provides HA fail over capacity for more than 1 ESX host at a time

I’ve held this post in my drafts because I wanted to try this configuration myself, but alas, I have never gotten around to it.  For those that can benefit from VC -less HA and give this script a test, let me (and Leo) know your results.

Leo’s post says: Read the rest of this entry »

Duncan over at yellow-bricks.com has posted a very helpful VMware HA troubleshooting tip. Changing the IP-address of an ESX host and HA deals with fixing HA issues that arise after changing the ip address of ESX hosts. In summary, Duncan was helping a colleague that was having trouble reconfiguring HA on an ESX cluster, and even though all the standard steps for resolving the issue were followed the HA feature could not be enabled on the cluster. Duncan was able to to identify that the issue was caused because a HA agent auto-generated file still contained the wrong ip address information. Specifically the /etc/FT_HOSTS file was the culprit.

Read the yellow-bricks.com post for the full details, but I am copying the t-shooting and resolution steps here for my future knowledge base. Read the rest of this entry »

Upgrading to ESX3.5 and VirtualCeter 2.5 Best Practices is a VMware KB article that lists best practice recommendations when performing the VI upgrade. As explained in the article:

This document provides additional steps which may be useful when upgrading to ESX 3.5 and VirtualCenter 2.5. It is assumed at this point that you have also read the Upgrade Guide.

Although the article contains 11 items in the list, in my opinion the last few are common steps (place the cd in the cd-rom drive of the host etc.) and not really best practices.
Regardless, review the following before performing the upgrade and follow these recommendations to minimize trouble.
Read the rest of this entry »

This weeks edition is centered on the topic of quick migration versus VMware HA and VMotion. We start with a post from the Windows Virtualization Team’s blog site and then explore some responses from a couple popular blogs in the virtualization community. Finally, if you have not seen Microsoft’s Quick Migration in action then check out the video at the end of this post. Links to the full posts are provided by clicking the section titles. Enjoy!

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Compared to VMware ESX Enterprise Edition, business continuity and high availability features are lacking when deploying Citrix XenServer “out of the box.” Specifically, XenServer does not have the built in equivalent to VI3’s HA feature. Also missing is a solution similar to VMware’s soon to be released Site Recovery Manager (SRM). However, Marathon Technologies and XenSource (now a division of Citrix) have worked together to develop everRun VM as a enterprise class answer to fault tolerant availability for Windows virtual machines hosted on Citrix XenServer. According to Marathon’s Director of Products, Michael Bilancieri, at a recent Atlanta “Virtualization for the Real World” event, the integrated solution will be generally available sometime in the 2008 Q2/Q3 time frame.

Quoting from the Best of VMworld (more on this award later in this post) white paper downloadable from the everRun link above:

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A Few Thoughts on Xen posted on blog.scottlowe.org got me thinking about the pricing differences between Citrix XenServer and VMware ESX Server. It is a general assumption that Xen Server is more affordable than ESX. I decided to figure out exactly what the products cost and how they compare to each other. I am not factoring in the cost of Sales and Support in this post because I would want that regardless of which vendor I choose.

I found Citrix XenServer list pricing from a Citrix presentation slide deck that was presented to me via a webinar several weeks ago. Click on the image to see a larger version. Read the rest of this entry »

How many VMs should run on each ESX host? The answer is determined mostly by the physical resources of the host’s platform (storage, ram, cpu, etc.). Before VI3 introduced ESX Clusters with DRS and HA squeezing as many VMs on each ESX host as possible was acceptable. Today it’s not just ESX host capacity, but ESX Clusters need to be take into consideration. Planning Cluster capacity means ensuring availability of VMs while maintaining acceptable host performance in a fail over scenarios.

First, what is a fail over scenario? The first thing that comes to mind is a problem. One or more of your ESX hosts unexpectedly crashed. This is considered unplanned downtime. Another fail over scenario to consider is planned downtime such as rebooting after applying ESX patches. For both of these types of scenarios you want to make sure your VMs stay online.

VMware’s solution for planned downtime is VMotion. The solution for unplanned downtime is the HA feature of ESX Clusters. When determining your ESX capacity be sure to allow room to leverage these features.

VMotion migrates a VM to a different ESX host without users losing connectivity. Evacuating an ESX server by VMotion enables you Read the rest of this entry »