VMware has announced a beta of their long talked-about Virtual Volumes (VVOLs) alongside the new beta of vSphere 6. So what are VVOLs, and how do they help you?
What are VVOLS?
VMware’s VVOLs, bring a refreshing change to how we manage and access virtual machines. Traditionally, virtual machines (VMs) were stored in SAN LUN constructs, where a SAN LUN was created with a particular RAID stripe, formatted with the VMware Virtual Machine File System, made into a datastore and used to store VM files like .vmdk and .vmx etc.
From a storage perspective, all that it can see is the LUNS. So, if you want to take a storage-initiated snapshot, you are snapshotting the LUN with a number of VMs. If you want to replicate VMs, you must replicate the LUN with a number of VMs. This means that each LUN must be presented to the virtual infrastructure in a redundant fashion to ensure availability -creating more landscape for configuration, optimization and troubleshooting. Finally, given these requirements, architects will have to align VMs according to LUN capacity and workload.
The issue is that storage has no awareness into the VMs that are inside that LUN. This lack of visibility makes it difficult to troubleshoot storage performance problems because you don’t always know which workload is problematic and the storage array won’t be able to tell you with any degree of certainty.
How do VVOLS work?
With VVOLs in place, the LUN construct is removed. VMware replaced the LUNS with one VVOL endpoint so the VMs can present virtual disks down to storage. This allows you to have thousands of VM volumes and detailed visibility into your storage environment. You simply present a raw storage array and the VVOLs will access the storage on their own.
Additionally, you will have a single connection from your vSphere hosts to your storage instead of many. Such a vast reduction in the mount points used in your storage environment will reduce management headaches and ease troubleshooting.
How do VVOLs Compare to vSAN?
The idea with Storage Policy-Based Management is that you are able to tie the storage requirements to the VMs (and thus to the application/workload). So, if you require greater performance, higher quality of service, or greater availability for a particular VM, then you specify it in VMware vCenter for that VM. Given that knowledge, the hypervisor (vSphere) talks to the storage (vSAN in this case) and tells the storage to meet the configured policies.
In the case of vSAN, you are able to replicate additional vSAN nodes in the cluster for VMs with higher availability requirements to ensure that, should more than one vSAN node fail, the application and it’s underlying storage will continue running.
The same is true for VMs that require higher performance. The storage will ensure that the VM is given greater performance by keeping more of the virtual disk data in flash (on each VSAN node) or by creating more replicas of the VM disk to improve read performance.
With VVOLs enabled in vSphere and on your storage array, storage-policy-based management can be applied to virtual machine disk files running on your SAN.
Why We Like VVOLS
VVOLs are incredibly beneficial for companies who need to increase the granular control and visibility of VMs on their storage array. VVOLs make VMs more efficient by allowing them to perform per-VM actions on their storage. VVOLs help datacenter admins to implement storage-policy-based-management (part of the Software-Defined Data Center concept), which allows them to ensure that VMs (and underlying applications) receive the quality of service and availability that they require.
Do I need to replace my storage?
Not necessarily, you don’t need VSAN to use VVOLs and, in most cases, you don’t need to replace your storage to use VVOLs. VVOLs work with many storage arrays already in use today.
What you can do right now
Right now, my recommendation is to watch some of the video demos of how VVOLs works on the VVOLs beta website and talk to a Softchoice storage resource to find out if your storage vendor does, or soon will, support VVOLs. Not every storage array is compatible today and not every storage array will be VVOL compatible in the future. If you are purchasing a new array soon, ensure that whatever storage you purchase is VVOL compatible for the future.
We concluded our webinar sessions convering the VMworld 2014 announcements. If you missed it, listen to the recording below! Our VMware experts took a deep dive into the announcements that will affect our clients the most.