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Show VLAN

Published by Steve Flanders on March 27, 2010

If you are a network administrator, then you probably know that on many switches typing the command ‘show run’ will display the running switch configuration and typing the command ‘show vlan’ will display the currently configured VLANs on the switch. If you are a system administrator, I would compare the ‘show run’ command to running ‘dmesg’ and the ‘show vlan’ command to running ‘ls’.
Why do I bring this up? Before answering, let me ask you a question: would you schedule a maintenance window to run these commands?

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Cloudy with the Chance of Computing – Part 2

Published by Steve Flanders on February 26, 2010

In my last blog entry about cloud computing, I answered the question: what is cloud computing? To do this, I defined the term cloud and then laid out some fundamental characteristics of cloud computing. Now, I would like to give a more formal definition of cloud computing. In perusing multiple articles on the topic, it has become apparent to me that there is no globally accepted definition of the term. This is understandable given the fact that cloud computing is still an evolving paradigm. In addition, many definitions that are available lack core and fundamental characteristics of the term.

Continue readingCloudy with the Chance of Computing – Part 2

Cloudy with the Chance of Computing – Part 1

Published by Steve Flanders on February 26, 2010

My good friend Luca sent me the following email a couple weeks back:

I thought you would find this Q&A in the newspaper entertaining. The Dallas Morning News just lost your company money:

Question: I’ve been listening to and reading a lot of tech news lately, trying to stay current, and there’s something that I’m having trouble understanding – cloud computing. What exactly does that term mean?

Answer: The cloud is a metaphor for ‘the Internet’. This started because in drawing flowcharts of various computer networks, the Internet was usually represented by a drawing of a cloud. Simply put, cloud computing means using the Internet to provide your programs and store your data. Instead of spending $300 on a new copy of Microsoft Office, you might find that Google’s online suite, Google Docs, will do just fine. With Google Docs, for example, you create your word processing or spreadsheet documents through Google’s Web site and you don’t have to install any software. It’s all stored ‘in the cloud.’ So ‘in the cloud’ has come to mean any online application or storage. Read the Wikipedia entry on cloud computing if you’d like to know more.

This got me thinking, what is cloud computing?

Continue readingCloudy with the Chance of Computing – Part 1

Have you restarted your management services today? (Cont.)

Published by Steve Flanders on February 26, 2010

In my last blog entry, I spoke about the importance of restarting management services when troubleshooting VMware ESX issues. One thing that I have noticed is that if you SSH to an ESX host and restart the management services you cannot cleanly exit out from the SSH session. To illustrate this point, SSH to a non-production ESX host and run the following commands:

You will notice the management services restart successfully, but your terminal hangs when trying to exit. What causes this and how can you fix it?

Continue readingHave you restarted your management services today? (Cont.)

Have you restarted your management services today?

Published by Steve Flanders on February 25, 2010

There are two VMware ESX commands that every VMware ESX administrator should know and master:

  • service mgmt-vmware restart
  • service vmware-vpxa restart

You may notice that for almost every VMware problem I blog about, the first step in troubleshooting is almost always restarting the management services. The reason for this is simple, it is the quickest and easiest way to fix a majority of the ESX problems experienced. I would compare it to restarting Windows in order to fix a Windows OS problem.
So what do these two services actually do?

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My take on what we're doing with Atmos

Published by Steve Flanders on February 25, 2010

One of the big news stories over the last couple weeks has been the announcement that EMC’s Atmos Online service offering will no longer be sold commercially. As you can imagine, this announcement is of great significance to Atmos Online customers, but it should not come as a surprise. As Chad over at Virtual Geek pointed out, Atmos Online was always intended to be a proof-of-concept and nothing more. He posted a good article about the changes entitled: Understanding what we’re doing with Atmos. In this article he highlights his views on the recent news. I would like to make a couple comments in regards to Chad’s article. Please be advised the views below are mine and do not reflect EMC’s stance on the topics.

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The Virtual Disk Is Either Corrupted Or Not A Supported Format

Published by Steve Flanders on February 23, 2010

Another interesting VMware issue came up this week. I was in the process of reconfiguring some ESX hosts and as such was forced to put these hosts in maintenance mode. As it turns out, one VM was located on the local storage of an ESX host and as such, I attempted to perform a Storage vMotion so the maintenance mode request would be successful. After about 20% completion, vCenter Server displayed the following error message, “The virtual disk is either corrupted or not a supported format.”

How do you troubleshoot this problem?

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