We have a DL380 G7 with 2x Xeon E5645 processors running at 2.4Ghz, on which we had ESXi 4.1 installed with a few VMs.
One of our VMs had Windows Server 2008 R2, with 4x vCPU and 12GB RAM. This was used for our accounts staff to run their reporting add-in for Excel.
We have just migrated the VM to a different DL380 G7 running 2x E5620 also at 2.4Ghz
I have made no changes to the config of the VM, so it still has 4x vCPU and 12GB RAM. However, when the users run their Excel reporting tool now, it looks to only be using on of the 4 vCPUs, causing the report to take forever to run.
Is there any part of the migration process that could have caused the VM to not correctly assign threads to each core?