Today a customer told me that he couldn’t vMotion virtual machines between a few hosts, he received this warning message:

Migration to host <<unknown>> failed with error Already disconnected

An unknown error has occurred.

vMotion migration socket connected returned: Already disconnected

Solution:

After some troubleshooting I’ve checked and tested:

– Same VMkernel (+ case sensitive) name;
– Same VLAN;
– Same subnet;
– Same default gateway;
– They configured unique ip-addresses;
– Host A can ping host B, vice versa;
– Ping is stable < 1 ms;
– But…

…reading KB1030267 I checked the MTU size, somebody configured the MTU size with a 9000 value at the Management / vMotion VMkernel..

The 9000 value was configured (at the hosts with the vMotion problem) but not at the physical switches, after revert to default value (1500) I was able to vMotion again, problem solved

Result:

sanderdaems

Sander Daems is founder and author of this blog and working as a Lead (Sr.) Consultant by UNICA ICT Solutions. Sander has over 15 years experience in IT, primary focus: virtualization and modern worksplace.

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Today I was importing some virtual machines (delivered by a 3rd party company) to the new vSphere 5 environment of a customer, the import was successful but after a vMotion I received this warning:

Module Migrate power on failed.
vMotion migration [168099940:1334234558581378] failed. The checkpoint data length (16384 bytes) or the offset (16776528 bytes) exceeds the maximum checkpoint data length (16777216 byte).

Solution:

The owner of the template installed the OS with a 1920 x 1080 resolution, after changing the resolution to 1280 x 1024 the GFX memory usage degraded to normal (under 30 MB).

After changing the resolution I was able to migrate the virtual machines,

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sanderdaems

Sander Daems is founder and author of this blog and working as a Lead (Sr.) Consultant by UNICA ICT Solutions. Sander has over 15 years experience in IT, primary focus: virtualization and modern worksplace.

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After we update ESX3.5 to ESX4.00 we noticed that some vms would not vmotion to a different host. Every time we tried we got the following error message.

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Daniel Buonocore

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