Distributed Resource Scheduler (DRS) performs load balancing across VMware ESXi hosts automatically.
vSphere DRS is a feature of vCenter Server and has the following two main functions:
* To decide which node of a cluster should run a VM when the VM is powered on, also known as intelligent placement.
* To evaluate the load on the cluster over time and either make recommendations for migrations or use vMotion to automatically move VMs to create a more balanced cluster workload.
vSphere DRS runs as a process within vCenter Server, which means you must have vCenter Server in order to use vSphere DRS. By default, DRS checks every five minutes (300 seconds) to see if the cluster's workload is balanced. DRS is also invoked by certain actions within the cluster, such as adding or removing a ESXi host, or changing the resource settings of a VM. When DRS is invoked it will calculate the imbalance of the cluster, apply any resource controls such as reservations, shares and limits, and, if necessary, generate recommendations for migration of VMs within the cluster. Depending on the configuration of vSphere DRS, these recommendations can be applied automatically, meaning that the VMs will automatically be migrated between hosts by DRS in order to maintain cluster balance.
You can set how aggressively DRS will automatically move VMs around the cluster. Looking at the DRS properties options, there are three selections regarding the automation level of the DRS cluster: Manual, Partially Automated, and Fully Automated.
Manual option
On every occasion you power on a VM the cluster prompts you to select the ESXi host where that VM should be hosted. The dialog box rates the available hosts according to the suitability at that moment: the lower the priority the better the choice.
Partially Automated option
DRS will make an automatic decision about which host a VM should run on when it is initially powered on, without prompting the user who is performing the power-on task, but will still prompt for all migrations on the DRS tab. Thus the initial placement is automated but migrations are still manual.
Fully Automated option
The Fully Automated option setting makes decisions for initial placement without prompting and also makes automatic vMotion decisions based on the selected automation level.
Migration Threshold ===> Conservative to Aggressive Five levels
Be aware that if you go for the most Aggressive settings, this can cause additional stress in your ESXi host environment because even a slight imbalance will trigger a migration.
vSphere DRS is a feature of vCenter Server and has the following two main functions:
* To decide which node of a cluster should run a VM when the VM is powered on, also known as intelligent placement.
* To evaluate the load on the cluster over time and either make recommendations for migrations or use vMotion to automatically move VMs to create a more balanced cluster workload.
vSphere DRS runs as a process within vCenter Server, which means you must have vCenter Server in order to use vSphere DRS. By default, DRS checks every five minutes (300 seconds) to see if the cluster's workload is balanced. DRS is also invoked by certain actions within the cluster, such as adding or removing a ESXi host, or changing the resource settings of a VM. When DRS is invoked it will calculate the imbalance of the cluster, apply any resource controls such as reservations, shares and limits, and, if necessary, generate recommendations for migration of VMs within the cluster. Depending on the configuration of vSphere DRS, these recommendations can be applied automatically, meaning that the VMs will automatically be migrated between hosts by DRS in order to maintain cluster balance.
You can set how aggressively DRS will automatically move VMs around the cluster. Looking at the DRS properties options, there are three selections regarding the automation level of the DRS cluster: Manual, Partially Automated, and Fully Automated.
Manual option
On every occasion you power on a VM the cluster prompts you to select the ESXi host where that VM should be hosted. The dialog box rates the available hosts according to the suitability at that moment: the lower the priority the better the choice.
Partially Automated option
DRS will make an automatic decision about which host a VM should run on when it is initially powered on, without prompting the user who is performing the power-on task, but will still prompt for all migrations on the DRS tab. Thus the initial placement is automated but migrations are still manual.
Fully Automated option
The Fully Automated option setting makes decisions for initial placement without prompting and also makes automatic vMotion decisions based on the selected automation level.
Migration Threshold ===> Conservative to Aggressive Five levels
Be aware that if you go for the most Aggressive settings, this can cause additional stress in your ESXi host environment because even a slight imbalance will trigger a migration.
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