If you were wondering why my blogging has dropped off in recent months, wonder no more. I’ve been fully immersed in the next release of VSAN. Today VMware has just announced the launch of VSAN 6.2, the next version of VMware’s Virtual SAN product. It is almost 2.5 years since we launched the VSAN beta at VMworld 2013, and almost 2 years to the day since we officially GA’ed our first release of VSAN way back in March 2014. A lot has happened since then, with 3 distinct releases in that 2 year period (6.0, 6.1 and now 6.2). For me the product has matured significantly in that 2 year period, with 3,000 customers and lots of added features. VSAN 6.2 is the most significant release we have had since the initial launch.
The following is by no means a comprehensive list of all of the new VSAN 6.2 features, but these are the major features, along with a few other features that I feel might be of interest to readers. In my opinion, we now have a feature complete product, and a world-class hyper-converged solution for any application. Read on to learn about the new features that we have added to this latest and greatest version of Virtual SAN.
This week Datrium announced that their DVX system is now generally available. I met these guys at VMworld 2015, and wrote a closer look at Datrium here. If you want a deeper dive into their solution, please read that post. But in a nutshell, their solution uses a combination of host side flash devices to accelerate read I/O, while at the same time writing to the Datrium hardware storage appliance (called a NetShelf). The NetShelf provides “cheap, durable storage that is easy to manage”. The DVX architecture presents the combined local cache/flash devices and NetShelf as a single shared NFS v3 datastore to your ESXi hosts.
We are hearing about a number of VSAN stretched cluster implementations going on at the moment, which is great news. I just set up such a configuration once again in my lab as we look at some various scenarios for the next release of VSAN. Now, for anyone looking at implementing VSAN stretched cluster, there is the VSAN 6.1 stretched cluster guide which should be your first port of call. However I noticed that once VSAN stretched cluster is implemented, you get a few warnings that you typically wouldn’t see in standard VSAN deployments. That is what I want to call out here.
This is something I only learnt about very recently, and something I was unaware of. It seems that we have made a major improvement to the way we do snapshot consolidation in vSphere 6.0. Many of you will be aware of the fact that when they VM is very busy, snapshot consolidation may need to go through multiple iterations before we can successfully complete the consolidation/roll-up operation. In fact, there are situations where the snapshot consolidation operation could even fail if there is too much I/O.
What we did previously is used a helper snapshot, and redirected all the new I/Os to this helper snapshot while we consolidated the original chain. Once the original chain is consolidated, we then did a calculation to see how long it would take to consolidate the helper snapshot. It could be that this helper snapshot has grown considerably during the consolidate operation. If the time to consolidate the helper is within a certain time-frame (12 seconds), we stunned the VM and consolidated the helper snapshot into the base disk. If it was outside the acceptable time-frame, then we repeated the process (new helper snapshot while we consolidated original helper snapshot) until the helper could be committed to the base disk within the acceptable time-frame.
By default VSAN.ClomMaxComponentSizeGB is set to 255GB. When Virtual SAN stores virtual machine objects, it creates components whose default size does not exceed 255 GB. If you use physical disks that are smaller than 255GB, then you might see errors similar to the following when you try to deploy a virtual machine:
There is no more space for virtual disk XX. You might be able to continue this session by freeing disk space on the relevant volume and clicking retry.
With the release of vSphere 6.0 earlier this year, VMware introduced the eagerly anticipated VVols or Virtual Volumes. As we see more and more traction around VVols, a specific question has come up a number of times already. The question is basically: “What happens to VVols if I lose my VASA Provider or my vCenter Server, or indeed both of these components? Will I still have access to my devices?”.
Attention VSAN users. A new Log Insight content pack has just been released specifically for Virtual SAN. For those of you not familiar with Log Insight, this product does automated log management through log analytics, aggregation and search. It allows administrators to analyze terabytes of logs, perform smart parsing to discover structure in unstructured data, and enable interactive, real-time search and analytics through a GUI-based, easy to use interface.