ecorvino
Contributor
Contributor

DRS keeps migrating same VMs

Hi, I have a cluster of about 20 hosts and 400 VMs.

Vcenter 6.5 U2a, hosts 6.5

DRS is fully automated with default threshold level.

DRS keeps migrating same 5 VMs hundreds time per day.

Is there a way to understand why is doing that and why is choosing always same VMs?

Thanks in advance

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9 Replies
sk84
Expert
Expert

I've seen this in conjunction with DRS rules. For example, with a rule that pinned some VMs to a few hosts and these hosts were heavily loaded. Then it moves the VMs that are least used back and forth all the time.

--- Regards, Sebastian VCP6.5-DCV // VCP7-CMA // vSAN 2017 Specialist Please mark this answer as 'helpful' or 'correct' if you think your question has been answered correctly.
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ecorvino
Contributor
Contributor

unfortunately this is not my case, all hosts are under 50% of utilization for both CPU and memory.

I'm wondering if is there a way to view inside logs why those vms are choosen?

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MikeStoica
Expert
Expert

How much RAM/CPU does those VMs have? Are those machines using memory/cpu intensive?

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ecorvino
Contributor
Contributor

are all small vms with 2/3 Gb of ram with cpu and ram in idle most of the time

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AmzSannegowda
Contributor
Contributor

Hi,

     were you able to rectify it was showing such behavior?

If you found answer please let me know.

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diegodco31
Leadership
Leadership

Hi

Do you have any DRS affinity rules or anti affinity rules?

Diego Oliveira LinkedIn: http://www.linkedin.com/in/dcodiego
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ecorvino
Contributor
Contributor

not yet, currently we planned to upgrade vcenter to 6.5 2d cause in release notes we've found this:

"vSphere DRS might run migrations of virtual machines even when a cluster seems balanced

In vSphere 6.5, if vSphere DRS detects in a balanced cluster an imbalance between two hosts larger than a set migration threshold, it might run some migration operations that do not effectively improve the balance between the two hosts.

This issue is resolved in this release"

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ecorvino
Contributor
Contributor

yes we have both

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depping
Leadership
Leadership

There's a fling for that!

It is called DRS Dump Insight: VMware Labs - Flings

it will help you figure out why VMs were migrated etc.

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