How vSphere's DRS Provides Effective Data Centre Management
VMware's vSphere has been an industry leading hypervisor for some while now, and ongoing enhancements keep its market leading position as an important part of many organization's software defined data centre (SDDC).
A key element in vSphere's virtual toolbox is distributed resource scheduler (DRS).
What does DRS offer?
It's a key benefit of software-based IT in that it provides a way for your existing resources to be adapted in real time to accommodate the changing demands on the infrastructure. This helps in no small way to enable existing hardware resources to meet differing demands - this is very useful in the event of some type of system problem such as a piece of hardware going down.
The DRS would re-deploy resources to keep things running while the hardware is brought back to life. Once operational, the DRS would re-deploy resources again to benefit from the hardware being back in service.
DRS shouldn't be confused with DPM (Distributed Power Management). This feature dynamically manages power to the hardware so as to save on energy costs and improve the organization's carbon footprint by powering down equipment when it isn't required.
DPM ties in with DRS: for example, when it decides extra capacity is required and powers a host back on, it will move VMs (Virtual Machines) back onto it using DRS to manage resources.
How DRS works
It effectively pools the system resources and uses them on a 'need' basis so as to cater for demands but not at the expense of under or over-utilizing resources.
When increased load is detected, DRS evaluates it based on pre-configured resource allocation rules and redistributes the load among the hardware servers to balance out the load demands from one source. A very useful feature for keeping, say, public websites up and running.
The DRS thus ensures that capacity is managed and given to the highest-priority application or VM for as long as is required. As soon as demand tails off, DRS will re-deploy the resources to other heavy demand situations if required.
It makes for a highly flexible and efficient system for managing resources and, in conjunction with the rest of vSphere and other software such as virtual SANs (Storage Area Network) from companies such as StorMagic, means existing resources can meet ever-changing demands as and when they arise.
The DRS feature on vSphere can be set up during initial installation of this hypervisor or later on, and is completed simply and quickly with a handful of clicks at a console.
A range of automation levels can be set for vSphere's DRS ranging from fully manual where migration recommendations are identified but require approval, to fully automated where migration options are identified by DRS and implemented automatically.
There is still some control even in automatic mode in that certain applications or VMs can be configured to never be migrated or permission has to be asked (as in manual mode).