Last week I had a question about how vSAN Enhanced Durability works when you have a limited number of hosts. In this case, the customer had a 3+3+1 stretched cluster configuration, and they wondered what would happen when they would place a host into maintenance mode. Although I was pretty sure I knew what would happen, I figured I would test it in the lab anyway. Let’s start with a high-level diagram of what the environment looks like. Note I use a single VM as an example, just to keep the scenario easy to follow.
In the diagram, we see a virtual disk that is configured to be stretched across locations, and protected by RAID-1 within each location. As a result, you will have two RAID-1 trees each with two components and a witness, and of course, you would have a witness component in the witness location. Now the question is, what happens when you place esxi-host-1 into maintenance mode? In this scenario, vSAN Enhanced Durability will want to create a “durability component”. This durability component is used to commit all new write IO to. This will allow vSAN to resync fast after maintenance mode, and enhances durability as we would still have 2 copies of the (new) data.
However, in the scenario above we only have 3 hosts per location. The question then is, where is this delta component created then? As normally with maintenance mode you would need a 4th host to move data to. Well, it is simple, in this case, what vSAN does is it creates a “durability component” on the host where the witness resides, within the location of course. Let me show you in a diagram, as that makes it clear instantly.
By adding the Durability component next to the witness on esxi-host-3, vSAN enhances durability even in this stretched cluster situation, as it provides a local additional copy of new writes. Now, of course I tested this in my lab. So for those who prefer to see a demo, check out the youtube video below.
Last week I saw an update from one of the Clumio founders on twitter. It reminded me that I had promised to take a look at their product. This week I had a meeting set up with Clumio and we went over their product and how to configure it briefly. Clumio is a SaaS based backup solution that was founded in 2017 by former PernixData, Nutanix, EMC folks. The three founders are Poojan Kumar, Kaustubh Patil, and Woon Jung, and those three you may remember from PernixData. One thing to point out is that they had 3 rounds of funding (~190 million dollars) so far and they came out of stealth around VMworld 2019. Coincidentally they won the Gold award for Best of VMworld in the data protection category, and best of show for the entire show, not bad for a first VMworld. I guess that I have to point out that although I would classify them as backup/recovery today, they are adding new functionality weekly and “backup/recovery” is probably not a fair category, data protection is more appropriate and it would not surprise me if that evolves to data management and protection over time. If you are not a fan of reading, simply head over to my youtube video on Clumio, otherwise, just continue below.
I created a list of recommended sessions for VMworld US, so I figured I would do the same for VMworld Europe. I am limiting it to 15 sessions for Europe and removed some of the sessions I had listed for the US and added some others for EMEA. I personally have 