To calculate the cluster IMBALANCE, DRS compares the Current Hosts Load STANDARD Deviation (CHLSD) to Target Hosts Load Standard Deviation (THLSD) and if

CHLSD < THLSD

Cluster is considered as imbalanced.

CHLSD Calculation:

DRS computes Normalized Entitlement (NE) of each Esxi hosts and the standard deviation associated with it. NE is nothing but calculation of how much resources are currently utilized out of total resources. NE is calculated by SUMMING up DYNAMIC entitlements (usage) of all VM’s that are running on an Esxi host and diving this by Esxi host capacity.

So, NE= Dynamic Usage of all VM’s / Total host capacity

THLSD Calculation:

THLSD is derived from DRS migration threshold which is defined at the time of configuring DRS. Each threshold level sets different imbalance tolerance margin. The aggressive threshold sets a tight margin allowing for little imbalance, while conservative thresholds tolerates bigger imbalances.

 To calculate the cluster imbalance, DRS compares the Current Hosts Load Standard Deviation (CHLSD) to Target Hosts Load Standard Deviation (THLSD) and if

CHLSD < THLSD

Cluster is considered as imbalanced.

CHLSD Calculation:

DRS computes Normalized Entitlement (NE) of each Esxi hosts and the standard deviation associated with it. NE is nothing but calculation of how much resources are currently utilized out of total resources. NE is calculated by summing up dynamic entitlements (usage) of all VM’s that are running on an Esxi host and diving this by Esxi host capacity.

So, NE= Dynamic Usage of all VM’s / Total host capacity

THLSD Calculation:

THLSD is derived from DRS migration threshold which is defined at the time of configuring DRS. Each threshold level sets different imbalance tolerance margin. The aggressive threshold sets a tight margin allowing for little imbalance, while conservative thresholds tolerates bigger imbalances.