VMware Virtual Volumes is a concept that represents a major paradigm shift from the way storage is used in VMware today.
Below is a short 5 minute video that explains the basic concept of VVOLs.
Additionally, knowing the difference between communicating with LUNs as in the old world and communicating with PEs (Protocol Endpoints) is crucial to understanding what VVOLs brings to the table and why.
In short, PE’s are actually a special LUN on the storage array that the ESXi server uses to communicate with the array. It’s not a LUN in the traditional sense, but more like a logical gateway to talk to the array. I would say in some ways it’s similar in function to a gatekeeper LUN on an EMC array. That LUN in turn maps to multiple sub-luns that make up the VM’s individual storage related components (vmdk, vswp, vmsd, vmsn etc). When the host wants to talk to a LUN, it sends the request to the address of the PE “LUN” with an offset address of the actual LUN on the storage array. Two things immediately came to mind once I understood this concept:
- Since all communication related to the sub-volumes is a VASA function, what happens when vCenter craps the bed?
- If I only have 1 PE, isn’t that going to be a huge bottleneck for storage I/O?
The answers to these and other questions are handily dealt with in a post here by VMware vExpert Paul Meehan. Again- the short version is that vCenter is not needed after the host boots and gets information on PE’s and address offsets. When it IS needed however is during a host boot. Secondly, I/O traffic actually goes through the individual volumes, not the PE. Remember, the PE is a logical LUN that serves as a map to the actual volumes underneath.
This brings me to the next video- understanding PEs. This link starts about 12 minutes into an hour long presentation where PE’s are talked about. Feel free to watch the entire video if you want to learn more!
Finally, let’s walk through how to set up VVOLs on your Nimble array. There are a few pre-requisites before you can start:
- NOS version 3.x or newer
- vSphere 6.x or newer
Here’s the step by step process:
- Connect to web interface of local array
- Click on Administration -> VMware integration
- Fill in the following information
- vCenter Name (this can be a vanity name- doesn’t have to be the address of the host)
- choose the proper subnet on your Nimble array to communicate with vCenter
- vCenter Host (FQDN or IP address)
- Check Web Client and VASA Provider
- Click Save (This registers vCenter with the storage array and installs the VASA 2.0 provider)
- Navigate to Manage -> Storage Pools
- Select the Pool in which you want to create the VVOLs (for most sites this will be default)
- Click New Folder
- Change the Management Type to VMware Virtual Volumes
- Give the folder a Name and Description
- Set the size of the folder
- Choose the vCenter that you registered above, then click Create
Now you have a storage container on the Nimble array that you can use to create VVOLs. Let’s look at the VMware side now:
- Connect to the vSphere web client for your vCenter 6 instance (this will not work with the thick client)
- Navigate to Storage and highlight your ESX server
- Click on Datastores on the right side of the window
- Click on the icon to create a new datastore
- Select your location (datacenter) then click next
- Select type VVOL then click next
- You should see at least one container- click next. If not, try rescanning your HBA’s in the web client and start again
- Assign which host(s) will need access to the VVOL and click next
- On the summary screen- click finish
You should now see a new datastore. Now let’s create a VM in the datastore and see what it looks like in the Nimble web interface!
- In vCenter, navigate to hosts and clusters
- Right click on your host to create a new virtual machine
- Click next under creation type to create a new virtual machine
- Give the VM a name, select the location where it should be created and click next
- Select the VVOL no requirements policy under VM storage policy
- Select the VVOL datastore that is compatible and click next
- Select ESXI 6.0 and later under the VM compatibility dtrop down and click next
- Choose the appropriate guest OS family and version then click next
- Adjust the virtual hardware to meet your needs and click next
- At the summary screen, verify all settings are correct and click Finish
Now if you navigate to Manage volumes in your Nimble web interface you will see multiple volumes for each VM you created. Instead of putting all the .vmdk, .vmx, .vswp and other files inside a single datastore on a single LUN, each object is it’s own volume. This is what allows you to set performance policies on a per VM basis because each volume can be treated differently. You can set high performance policy on your production VM’s and low performance on dev/test for example. Normally you would have to split your VMs into separate datastores and manage the performance policies on a per datastore level. The problem with this is that you still have no visibility into each VM in that datastore at the storage layer. With VVOLs, you can see latency, throughput and even noisy neighbor information on a per VM basis in the Nimble web interface!