Monday, August 29, 2016

#VMworld Virtual Volumes Technical Deep Dive

Presented by Patrick Dirks and Pete Flecha @vPedrowArrow

Customers face several challenges with storage today: Silo'd Management with a fragmentation of tools, Rigid Infrastructure with a static class of services that is both Complex and time consuming. Key Issues with Traditional Storage Management is that visibility is difficult, capabilities are applied at the LUN level. In addition a set of vendor specific requirements are usually required to turn on advanced features.

The secret sauce of Virtual Volumes "VVOLs" is the Storage Policy-Based Management. This allows capabilities to be applied at the virtual Disk level. It also enables volumes can be consumed on demand. VVOLs allow you to move from a LUN centric architecture to a simplified service/policy model. Virtual disks are natively represented on the arrays. VVOL leverages vStorage APIs for Storage Awareness or a "VASA" Provider for the management data outside the data path. The VASA provider is provided by the storage vendor.

There are five different types of recognized virtual volumes: config (logs), data (VMDKs), MEM (Snapshots), SWAP and other VMware specific files. To setup VVOLs the Storage Admin sets up a Storage container with the capabilities the SAN provides. A Storage container on the SAN is associated to a Virtual Volume on the Host. A Storage Container is not a LUN however, it is more like publishing the capabilities of the SAN. The vSphere Admin can apply those features at a VM level through policy

In addition a Protocol Endpoint is defined to provide an I/O target for commands. There is no storage capacity with a Protocol Endpoint. These are presented by the VASA provider. 

The Policy determines the placement of the VM on a virtual volume. There is a difference between Storage Capabilities and a VM Storage Policy but these often get confused. Storage Capabilities provide SAN features. The VM admin defines a VM Storage Policy based on the requirements needed by the VM. When you provision, the Automated Policy engine will show you the datastores that are compliant with the VM's policy requirements.

From a VM Admins perspective, it looks similar in vCenter to the way datastores are presented without VVOLs with the exception of the addition of the storage policies. From a storage admins perspective, they see Storage Containers but also which VMs are associated to them.

If there is I/O demand from a VM perspective the Array can request the host do a rebind by reseting the Protocol Endpoints to change the flow of I/O providing better controls for I/O demands.  With VVOLs, Snapshots are also enhanced because the I/O is offloaded to the Array so that they are extremely quick as it is just a metadata change on the storage side.  

This is the first release of VVOLs and it requires vSphere 6.0 and above. Todays session will be repeated Wednesday at 1 PM.

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