Saturday, September 7, 2013

VMworld 2013 – VSANs

One of the most interesting things to come out at VMworld 2013 is VMware VSANs. At a high level VSANs aggregate the local storage either internal or Direct Attached to ESX servers and creates a VSAN Datastore. The VSAN datastore supports all of the capabilities of traditional external storage attached to ESX Clusters. To be clear this isn’t simply a virtual storage appliance, this is integrated at the Hypervisor level. VMware pointed to the numerous advantages of being able to manage storage that is integrated directly into the solution. It is inherently VM aware and more than that they have the ability to understand workloads in real time and make adjustments based on the SLAs you define.
Here are some of the specific use cases that were highlighted:
  • VDI environments 
  • Test / DEV 
  • ROBO 
  • Tier 2 and Tier 3 Applications 
  • DR Target 

VMware pointed out how their performance testing showed the VSAN approach would provide performance comparable to all Flash arrays at a significantly lower price point.

Here are some notes from the sessions I attended:
  • They really don’t want you to use intelligent storage arrays with VSANs. Their software works best when they have direct access to each physical disk. If you are using an internal RAID controller it needs to be setup in pass through or HBA mode. 
  • You need at least 3 nodes with internal storage to setup a VSAN and each host must have at least one SSD and one magnetic disk. The SSD is used for caching not as a storage tier. 
  • 8 Nodes is the max. You can have more than 8 nodes in the cluster but you can only use the storage from 8 nodes. 
  • Redundancy is based on having multiple copies of the data and you can tell it how many failures you want to be able to withstand. You also have the ability to do striping – RAID 0. These settings are applied at the virtual machine level. 
  • GA Target is the first half of 2014 

So what does all this mean?

Well with most new solutions it will take some time to see how it all fleshes out. What we know is that we are going to have more options, different ways we can provide storage and solve challenges. We know that VMware is proceeding down multiple paths. They know that storage is still a major challenge for most organizations and there is unlikely to be a single solution that meets every need which is why they are continuing to work with all of the storage manufacturers to more tightly integrate with their technologies.

Storage whether internal and driven by software or external and using intelligent controllers needs to be integrated from a management standpoint. You need to be able to provision and consume storage as efficiently as you now can with compute resources. Storage needs to be more dynamic and able to adapt to workloads based on the requirements of the upper level services being provided. Storage management in general needs to be smarter, it needs to know more than just blocks of data, it needs to understand what the data is – this is a VM, this is an OLTP database, this is a data warehouse and these are the structures that make up those databases. This level of understanding allows the data management layer, wherever it resides to be more effective.

VMware isn’t interested in selling internal storage versus external storage so much as they are interested in selling more VMware and making their solutions more capable, at a lower cost, is in their best interest. I don’t expect to get a lot of calls from clients that need help decommissioning their VMAX or VSP so that they can move everything to internal storage but I do expect VSANs to be a viable and accepted option in many cases.

We’re signed up to get the beta and when we do we will put it through its paces in our lab and let you know what we find.


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