With the release of VMware’s vSphere 6 and VVOLs. I have had a several customers ask me questions regarding VVOLs and how they compare to Tintri’s VM-Aware storage platform. There lies some confusion on both technologies. For example, there is a notion that VVOLs give non-Tintri storage arrays the same capabilities as Tintri. Now there some some similarities between the two but it’s important to understand that both technologies are trying to solve the same problem but from different perspectives. So I decided I decided to dive a little deeper on both technologies and hopefully clear up some confusion.
What problems are we trying to solve?
Before we dive into both VVOLs and Tintri’s VM-Aware storage its important to understand what problem are we trying the solve. One of the big challenges as a VMware environment starts to grow becomes storage management and data protection. VMware has operated in a data store model since it’s initial release a decade ago. A data store can be a VMFS (VMware File System) data store on top of a block storage devise like a FC or iSCSI LUN or it can be file based using NFS. These data stores are basically pools of storage for VMs and here lies the issue. Each data store can have dozens or even hundreds of VMs which have their own storage characteristics and needs for the application. In the data store model your point of management is the data store which is cumbersome from a performance, troubleshooting and data protection standpoint. This is exacerbated in larger enterprise environments when your dealing with thousands of VMs. So how do we change this paradigm? We move away from the data store model to a VM based storage model. What does that mean? That means that we change the focus from the data store to what really matters most, the VM and most importantly the application. This is what is ultimately brought to the table with both VVOLs and Tintri’s VM-Aware storage.
What is Tintri’s VM-Aware storage?
Tintri’s released VM-Aware storage back in 2011 with the announcement of their VMStore platform. This was a few years before VVOLs were officially released with vSphere 6. VM-Aware storage allows Tintri to gain visibility to a virtual machine that’s running on top the Tintri file system. This visibility is gained through VAAI (VMware API for Array Integration) which allows Tintri to connect to vCenter and gain understanding of the Virtual Machine environment. Tintri is NFS only, which makes it easier for integration and overall improves the VMware storage experience. The Tintri VMStore doesn’t operate in Volumes but in VMs. Which makes overall storage management a lot easier and more efficient.
Tintri leverages zero based pointer snapshot technology which makes snapshots and clones almost instantaneous during creation. That coupled with VM level storage management makes it easier to design a data protection strategy. This same snapshot technology is used for replication and this too a VM level and not Volume based. This helps you design a more granular RTO/RPO for Disaster Recovery.
Tintri’s VM-Aware storage also has benefits from a performance standpoint. Performance characters like QoS and latency can be fined tuned for individual VMs versus other storage platforms where VMs have to be grouped by LUN or Volumes. This approach gives the VMware Administrator more flexibility when it comes to carving out performance characteristics. This overall simplification of storage makes it easier for a “non-storage” administrator to provision storage that works and performs out of the box.
What are VVOLs?
VVOLs or Virtual Volumes are similar to Tintri’s VM-Aware storage but also have some noticeable differences. VVOLs allow storage vendors to gain a level integration and better management capabilities at the VM-level. This level of integration is accomplished using VMware’s VASA or VMware’s API for Storage Awareness. VASA lies between the ESX host and the storage array and it facilitates the communication between the two. VASA 2.0 which was released with vSphere 6.0 is the only version that supports VVOLs. The previous version of VASA that ran on vSphere 5 is not supported. So an upgrade of your VMware environment will be in order if you are running an older version of VMware.
On the storage side, there a couple of things to take into consideration. First, does my storage array support VVOLs? If the answer is no, then newer hardware will be needed in order to get support. Even with vSphere 6, you still need the storage array to support VVOLs. Second, if your storage array does support VVOLs. A software or firmware upgrade my still be needed in order to turn on VVOL support. If you fall under the first option. The need to purchase a new storage array. Just remember, that not all storage arrays are equal when it comes to VVOLs. Each implementation will be dependent on the overall quality of their product.
Once you get things squared away on both the VMware and storage side. There is an important consideration with VVOLs that needs to be mentioned as you start to design phase. Each VM will need 3 to 4 VVOLs at a minimum in order to get full benefits of VVOLs. You will need a Configuration VVOL, vSwap VVOL, Data VVOL and Snapshots VVOL at a minimum. If you are presenting multiple data VMDK files to a VM then those will need to be VVOLs as well. So a storage arrays ability to scale is important as the number of VMs in your environment increases. This goes back to the previous paragraph. Pick you storage vendor and array wisely.
How do they compare?
So how does Tintri’s VM-Aware storage compare to VVOLs. Let’s break this down by first discussing where both technologies overlap.
VM Level Snapshots: Tintri and VVOLs both support VM Level Snapshots. This is where both technologies can help from a data protection strategy. The ability to snapshot at the VM Level versus the data store level. The only difference lies in that VVOLs will leverage whatever Snapshot technology is available to it on the storage side. So it goes back to understanding that each storage platform is different and with snapshots your mileage could very when it comes to overhead.
VM Level Clones: Tintri and VVOLs both support VM Level Clones. This too (like snapshots) moves cloning from the data store level to the VM Level. Like with snapshots, there are different implementation of cloning. So if cloning is an important part of your overall strategy for development or test/dev its important to understand your overall implementation. Some cloning technologies are more space efficient than others.
VM Level Replication: This is where you start seeing some difference between VVOLs and Tintri. Tintri supports VM Level Replication. The ability to replicate at the VM level is a nice feature for more granular failover of VMs and allows for more tightly control RPO/RTO. With VVOLs you can replicate at the VVOL level which a first glace might seem to be the better option. However, if you think about it. This is where you could run into issues from a storage management perspective. It most cases you want to keep the same RPO/RTO for an entire VM. I’m guessing some instances having it at a per VVOL level would have some advantages depending on use cases.
VM Level QoS: Tintri has full support for VM Level QoS. However, VVOLs don’t have any ability to control QoS or add that functionality to storage array. Storage QoS is still a fairly new features and is not supported by all storage vendors and the ones that do support it are LUN or Volume bases. With that said, there are some inherent advantages to VM Level QoS. Each QoS policy and be fine tuned for each VM in a Tintri solution but there could be some advantages to LUN level as well. It all depends on how your environment would best benefit from QoS.
Another big take away is that Tintri supports vSphere 4, 5 and 6. VVOLs are a new feature of vSphere 6 which will require an upgrade of your VMware environment and most likely some kind of hardware and/or software upgrade to your storage environment. For a more detailed breakdown check out this whitepaper by Tintri.
So you can see. That both Tintri’s VM-Aware storage and VVOLs are changing the paradigm on how storage will be administered going forward in a virtual environment. It is important to understand how each technology works and that both have advantages even if there is some overlap in features. The Challenge with VVOLs now is the fact that this is a new technology and you are dependent on the storage vendor and the quality of their API(s) and feature set. For example, the max number of VVOLs supported between storage vendors as of this writing ranges from the thousands to over a million. That scalability will be needed for large and growing virtual environments Tintri has been doing VM-Aware storage since their inception several years ago and once VVOLs mature a bit. Tintri and VMware will have some of the best integration when it comes to bridging the gap between storage and virtualization.