VMStew
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VCentre - DRS question

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Hi Guys,

Just FYI, I am new to the organisation... so just trying to get a handle on thier envirnoment.

I have noticed an information/warning that there is a load imbalance... vSpere DRS has been set to “Fully automated” but no machines have been added to a DRS group?? Can you confirm for me, do machines need to be allocated to an appropriate group before DRS will take affect?

Also, what do you guys set your tagrget host load threshold to? our is currently set to <= 0.035

Thanks,

Stuart.

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frankdenneman
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Hi Stuart,

No virtual machines have to be assigned a specific group for DRS to be able to load balance the virtual machines across the hosts in a DRS cluster. DRS is enabled on cluster-level and the cluster becomes the load balancing domain for DRS. This means that - if specified otherwise - all virtual machines inside the cluster are valid canidates for load balancing.

It is recommended to leave the DRS load balancing threshold to moderate. The value you provide is the Target Host load standard deviation, and this is the target for DRS to achieve. THLSD and CHLSD are quite advanced topics, if you want to learn more I would recommend you to buy one of the books Duncan Epping and I co-authored on vSphere clustering.

Now back to your problem, there is an imbalance and DRS warns about not able to load balance. What is the exact warning?

Blogging: frankdenneman.nl Twitter: @frankdenneman Co-author: vSphere 4.1 HA and DRS technical Deepdive, vSphere 5x Clustering Deepdive series

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frankdenneman
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Hi Stuart,

No virtual machines have to be assigned a specific group for DRS to be able to load balance the virtual machines across the hosts in a DRS cluster. DRS is enabled on cluster-level and the cluster becomes the load balancing domain for DRS. This means that - if specified otherwise - all virtual machines inside the cluster are valid canidates for load balancing.

It is recommended to leave the DRS load balancing threshold to moderate. The value you provide is the Target Host load standard deviation, and this is the target for DRS to achieve. THLSD and CHLSD are quite advanced topics, if you want to learn more I would recommend you to buy one of the books Duncan Epping and I co-authored on vSphere clustering.

Now back to your problem, there is an imbalance and DRS warns about not able to load balance. What is the exact warning?

Blogging: frankdenneman.nl Twitter: @frankdenneman Co-author: vSphere 4.1 HA and DRS technical Deepdive, vSphere 5x Clustering Deepdive series

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VMStew
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Hi there,

Thanks very much for the reply! that is exactly the info I needed. There is no issue now, after going back over the events/logs I can see that DRS is working fine... I just happend to look when there was an large imbalance which the automated process had not yet rectified. So it is all good!  Smiley Happy

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