Category Archive: 5.0

May 31

Which isolation response should I use?

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May 31, 2012

I wrote this article about split brain scenarios for the vSphere Blog. Based on this article I received some questions around which “isolation response” to use. This is not something that can be answered by a simple “recommended practice” and applied to all scenarios out there. Note that below has got everything to do with your infrastructure. Are you using IP-Based storage? Do you have a converged network? All of these impact the decision around the isolation response.

The following table however could be used to make a decision:

Likelihood that host will retain access to VM datastores Likelihood that host will retain access to VM network Recommended Isolation policy Explanation
Likely Likely Leave Powered On VM is running fine so why power it off?
Likely Unlikely Either Leave Powered On or Shutdown Choose shutdown to allow HA to restart VMs on hosts that are not isolated and hence are likely to have access to storage
Unlikely Likely Power Off Use Power Off to avoid having two instances of the same VM on the VM network
Unlikely Unlikely Leave Powered On or Power Off Leave Powered on if the VM can recover from the network/datastore outage if it is not restarted because of the isolation, and Power Off if it likely can’t.

“Which isolation response should I use?” originally appeared on Yellow-Bricks.com. Follow us on Twitter and Facebook.
Available now: vSphere 5 Clustering Deepdive. (paper | e-book)

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Permanent link to this article: http://www.startswithv.com/2012/05/31/which-isolation-response-should-i-use/

May 25

How do I use das.isolationaddress[x]?

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May 25, 2012

Recently I received a question on twitter how the vSphere HA advanced option “das.isolationaddress” should be used. This setting is used when there is the desire or a requirement to specify an additional isolation address. The isolation address is used by a host which “believes” it is isolated. In other words, if a host isn’t receiving heartbeats anymore it pings the isolation address to validate if it still has network access or not. If it does still have network access (response from isolation address) then no action is taken, if the isolation address does not respond then the “isolation response” is triggered.

Out of the box the “default gateway” is used as an isolation address. In most cases it is recommended to specify at least one extra isolation address. This would be done as follows:

  • Right click your vSphere Cluster and select “Edit settings”
  • Go to the vSphere HA section and click “Advanced options”
  • Add “das.isolationaddress0″ under the option column
  • And add the “IP Address” of the device you want to use as an isolation address under the value column

Now if you want to specify another isolation address you should add “das.isolationaddress1″. In total 10 isolation addresses will be used. Keep in mind that all of these will be pinged in parallel! Many seem to be under the impression that this happens sequential, but that is not the case!

Now if for whatever reason the default gateway should not be used you could disable this by adding the “das.usedefaultisolationaddress” to “false”. A usecase for this would be when the default gateway is a “non-pingable” device, in most scenarios it is not needed though to use “das.usedefaultisolationaddress”.

I hope this helps when implementing your cluster,

“How do I use das.isolationaddress[x]?” originally appeared on Yellow-Bricks.com. Follow us on Twitter and Facebook.
Available now: vSphere 5 Clustering Deepdive. (paper | e-book)

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Permanent link to this article: http://www.startswithv.com/2012/05/25/how-do-i-use-das-isolationaddressx/

May 16

KB article about SvMotion / VDS / HA problem republished with script to mitigate!

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May 16, 2012

Just a second ago the GSS/KB team republished the KB article that explain the vSphere 5.0 problem around SvMotion / vDS / HA. I wrote about this problem various times and would like to refer to that for more details. What I want to point out here though is that the KB article now has a script attached which will help preventing problems until a full fixed is released. This script is basically the script that William Lam wrote, but it has been fully tested and vetted by VMware. For those running vSphere 5.0 and using SvMotion on VMs attached to distributed switches I urge you to use the script. I expect that the PowerCLI version will also be attached soon.

http://kb.vmware.com/kb/2013639

“KB article about SvMotion / VDS / HA problem republished with script to mitigate!” originally appeared on Yellow-Bricks.com. Follow us on Twitter and Facebook.
Available now: vSphere 5 Clustering Deepdive. (paper | e-book)

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Permanent link to this article: http://www.startswithv.com/2012/05/16/kb-article-about-svmotion-vds-ha-problem-republished-with-script-to-mitigate/

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