The Virtual SAN: The evolution of storage

May 8, 2015
The Virtual SAN: The evolution of storage

By Ian Jansen Van Rensburg, Senior Systems Engineering Manager at VMware Southern Africa

Storage: the next revolution has already begun. It is the era of agility and flexibility as the virtualised environment undergoes a transition from the virtual server sprawl of early implementations to something far richer and easier to manage. Businesses have complained that the cost of storage is too high and still incredibly difficult to manage, even as applications and servers are virtualised. Now there is a way to address these issues and create an environment that ticks all the boxes – ease of use and management, robust implementation and impressive functionality and scalability.

A new software-defined storage approach is needed in order for the storage-related operational complexities and cost challenges to be dealt with more effectively.  Already the enterprise has experienced significant cost benefits, flexibility and scalability through virtualised CPU and memory resources. The network is speeding into the race with the software-defined data centre (SDDC) that allows for the internal network to be provisioned around the virtual machine rather than being tied to the hardware.

Currently, everything revolves around Logical Unit Numbers (LUNs) upon which virtual machines rest and within which applications run. The management processes take time to configure and they are often quite difficult to perform. Add to this the fact that storage devices require exceptional random read and write performance thanks to the fact that different applications on the same VM have differing I/0 requirements.

Enterprises have also struggled with space limitations thanks to over-provisioned storage that was often underutilised, primarily due to how simple it was to provision virtual machines and their associated disk images.

The solution to these challenges is both elegant and efficient. The SAN is now virtual – the hypervisor managing both the directly attached storage and the network connected storage and delivering it as a highly-configurable SAN.  Each node now uses a minimum of one solid state drive and one spinning drive. The latter serves as the primary storage while the former is used for read caching and write buffering.

The SAN is enabled directly within the hypervisor kernel and can be activated with only two clicks of the mouse and the policy management is now at the virtual machine level for maximum control, rather than per LUN. As the hypervisor sits between the application and the hardware, all I/O goes through this layer and, because it is simple to identify which VM or application it’s coming from, smart things can be done. The hypervisor also understands what the storage system has to offer and can communicate its needs accurately.

This virtual SAN model can be immediately implemented to great effect in a variety of use cases and virtual desktops can be rolled out at a lower cost with predictable performance. Storage can also be provisioned quickly without the need to purchase expensive external storage, a disk can be added to a host or a host to a cluster and then the hypervisor handles the rest. The virtual SAN fits neatly into the software-defined data centre approach. For storage and the workloads that sit atop it, this now allows for resources to be abstracted and pooled and its management automated through policy provisioning. The automated deployment of a new application can be swiftly done through a common set of APIs.

The virtual SAN has enormous potential, even as an inexpensive disaster recovery option which redirects a snapshot or backup to any target within the cluster. Enterprises now have the capability to build up environments made up of dense building blocks with storage resources near where they are needed. This is the new future of storage and it is truly a far more cost-effective, efficient, simple and scalable solution than those that have gone before.


 
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