Yellow Bricks

by Duncan Epping

Another colleague blogging…

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It seems like blogging is also a trend over at Ictivity. Another colleague of mine just recently started blogging. His blog is not fully functional(RSS) but there are a couple of interesting reads over there. Rene Jorissen is one of the upcoming “Connectivity” Consultant who mainly focuses on Cisco.

Check out his blog.

A couple of short outtakes:

Source: Our VMware consultants always choose Route based on IP hashes as load-balancing algorithm. This means that load-balancing happens on layer 3 of the OSI model (source-destination-IP)

Source: CactiEZ is a software appliance, which is up and running in half an hour. After that you just add some devices and you can generate some nice bandwidth statistics with the help of RRDTool.

Source: QoS is an important tool to assign VoIP traffic more preference over “normal” traffic. Important for QoS tools to function correctly is placing different kinds of traffic in different queues. To place traffic in different queues, traffic should be classified.

VM’s automatically renamed

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Yesterday evening I witnessed a weird phenomenon. We had to bring down a complete environment to move a 19″ rack to a different location. We switched the SAN on, waited a couple of minutes and switched the ESX hosts on. When the ESX hosts finished booting we booted the VirtualCenter. Everything looked normal in the VI Client. I had all connections to the SAN and all ESX Hosts were up and running. So I decided to power up the first VM, it was a VM named LNX01. Within a second the VM got renamed to LNX05(1). I though I was going nuts. I checked the settings of the renamed VM and indeed it was pointing out to the LNX05 diskfiles/vmx.

Maybe it was just me, or this one VM so I decided to give another one a try, I powered up LNX02. Same happening here, within a second the VM was renamed to PS01(1) and booted fine. The settings were pointing out to PS01. I checked a couple of VM’s but could not find anything weird. I restarted the VirtualCenter service just to be sure. I started the VM LNX03 and again it was renamed… Than I decided to restart the “mgmt-vmware” services on all of the ESX hosts and the problem never returned again. It seems like VirtualCenter had a different view than the ESX hosts had. But I can’t think of a logical reason what could cause this. I searched the knowledge base but could not find any related problems, well besides an old article based on VirtualCenter 1.2.

MS Virtualization blogs and VMotion

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Recently there was an article published on the Microsoft Virtualization Blog which compared Hyper-V’s High Availability/Quick Migration capabilities to VMware’s VMotion. (VMblog pointed me towards the article) In the second article the writer responds on a large amount of reactions he had regarding VMotion being superior:

After my last blog I received almost two dozen email telling me that VMotion was far superior for unplanned host downtime and that it was a much better HA solution because it could live migrate virtual machines. I’ve heard this fallacy espoused for many years and, folks, this simply isn’t the case.

In the case of unplanned downtime, VMotion can’t live migrate because there is no warning. Instead you must have VMware HA configured and the best it can do is restart the affected virtual machines on other nodes which is the same as what is provided with Windows Server 2008 Hyper-V and Failover Clustering.

I can imagine why people reacted, in the first post the writer only mentioned VMotion. For unplanned downtime VMware doesn’t use VMotion because when it’s unplanned the VM’s get cutoff and will be restarted on another host with the use of HA(VMware High Availability). There’s no need for a migration when a VM is powered off.

Indeed Microsoft can do the same with the use of Clustering. But can you live migrate virtual machines when a server needs maintenance? No, at this moment that’s not possible. In other words, you will have to wait for a suitable moment… planned downtime, probably after business hours. But in a 24×7 environment will there ever be a suitable moment? Even when your business isn’t 24×7, if there’s a possible hardware failure would you want to wait? But when you have a 8:1 consolidation ratio you probably will not be the most popular system engineer when “quick migrating” the file server or the mail server especially when these VM’s have a lot of RAM assigned.

Besides that, with the upcoming new product, Continuous Availability, even unplanned downtime will not crash your VM. CA will constantly mirror your VM to another host, like a continous VMotion I guess, and when the active host fails the standby host will become active. In other words, no unplanned downtime anymore.

Powershell VI Toolkit

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Today I combined a couple of Powershell scripts which as a result gives a nice html formatted file with a table. This table contains all VM’s with their VMware Tools status and version. I’ve uploaded the script here. The outcome looks like the following:

As you can see, the VMware tools status is “ok” but the versions are totally out of line. I know there are already a few tools handling this but as far as I know none of them creates a text/html output file.

Clean SP1 junk, VSP1CLN

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My colleague Edwin pointed me out to this tool to remove the junk Vista’s SP1 leaves behind.

The Windows Vista Service Pack 1 (SP1) Files Removal Tool (VSP1CLN.exe) can be used to remove the files that are archived after Windows Vista SP1 is applied. Running this tool is optional.

Installing Windows Vista SP1 increases the amount of disk space that is used by the operating system. This space is used to archive files so that SP1 can be uninstalled. Typically, you should run VSP1CLN.exe if you want to reclaim this disk space after applying SP1 and if you will not need to uninstall SP1.