DRS/DPM not putting hosts into Standby Mode

Products

• VMware vCenter Server

Issue/Introduction

DPM is scheduled at 8 PM to put hosts into standby, and disable at 6 AM taking hosts out of standby.

DPM now chooses not to put hosts into standby at all some nights or delays the standby process until 11 PM or even later.

The Platform was not under more load there is no difference in load now, from when it was first deployed.

DRS score checked, and all have a 99% score.

 

Environment

vCenter 8

Cause

DPM will not provide the recommendation to put a host into standby mode if it calculates that the cluster will become utilized over 81% CPU & MEM, with the remaining hosts; or if the host utilization itself will cross a high threshold. It calculates this by simulating moving the VMs between hosts.

DPM checks this by doing a sanity step to see if the previous calculation matches the current iteration - if an iteration is successful (cluster not crossing 81% utilization), the sanity step will trigger to see if the current iteration matches the previous successful one. If the current iteration detects that some hosts receive more VMs than the successful iteration: DPM will not provide the standby recommendation. In order for DPM to provide the recommendation - the results of the sanity step and the successful iteration it's based off of, must match.

The cause of the issue is the sanity step does not sort the VMs by CPU/MEM entitlement - causing the results of the sanity step to differ from the previous successful iteration. Therefore DPM does not provide it's recommendation.

 

 

Resolution

VMware Engineering is actively developing a resolution for this issue which will be released in a future update to vCenter Server.