VSAN – Misconfiguration Detected

Although Cormac Hogan already wrote about this I figured I would repeat some of his work. It seems like various folks are hitting this issue where an error is thrown while configuring VSAN: Misconfiguration Detected. The misconfiguration in this case refers to how the physical network has been configured. In order for VSAN to be successfully configured your layer 2 VSAN network will need to be enabled for multicast traffic. (below a screenshot of the error which I borrowed from Cormac… thanks Cormac)

In order to successfully configure VSAN you can do two things, now lets be clear that I am not the networking expert and personally I would always advise to discuss with your networking team what the best option is. Here are your two options:

  • Enable IGMP Snooping for your VSAN network (VLAN) and define an IGMP Snooping Querier. Default setting on most Cisco switches is IGMP Snooping enabled but without an IGMP Snooping Querier. In this configuration VSAN will not be able to configure correctly!
  • Disable IGMP Snooping for your VSAN network (VLAN). Please note that you can typically disable IGMP Snooping globally and per VLAN, in this case if you want to disable it… disable it on your VLAN!

Please consult your network vendor documentation on how to do this.

Top 25 bloggers 2014 results are out…

The top 25 bloggers 2014 voting results are out. This year the competition was insane, and I know that I say this every year but if you look at bloggers like Cormac Hogan, Derek Seaman, Frank Denneman, Chris Wahl and William Lam you know what I am talking about.

1400+ people voted, 15 new blogs in the top 50, 5 new blogs in the Top 25, and a new blog in the Top 10. A big thank you to every who has voted for me again, I am honored and humbled to have been voted number 1. I want to call out the top 5 as I have worked closely with most of them the last years and it has been a great pleasure: William Lam(2), Frank Denneman(3), Cormac Hogan(4) and Scott Lowe(5). Each of them has consistently produced excellent material. I have been very very impressed by what they’ve released over the last year and hope everyone keeps putting out their material as I very much enjoy reading it.

Congrats to everyone else who made the list, if you are curious who they are head over to the full top bloggers list on Eric’s blog. Maybe even better, watch the awesome show Eric, John, Rick and David recorded… It is very entertaining!

Selecting a disk controller for VSAN using the HCL

As this was completely unclear to me as well and I started a thread on it on our internal social platform I figured I would share this with you. When you go through the exercise of selecting a disk controller for VSAN using the VMware Compatibility Guide (vmwa.re/vsanhcl) you will see that there are 4 “features” listed. The four features describe how you can use your disk controller to manage the disks in your host. This is important as selecting the wrong disk controller could lead to unwanted side effects.

Let me list the four features and explain what they actually mean:

  • Virtual SAN – SAS
  • Virtual SAN – SATA
  • Virtual SAN Pass-Through
  • Virtual SAN RAID 0

Virtual SAN – SAS / SATA and Pass-through are essentially the same thing. Well not entirely as it is implemented in a different way, but the result is the same. What this does is serving the disks straight up to the hypervisor. This functionality literally passes the disk through to ESXi, and avoids the need to create a RAID set or volume for your disks. This is by far the easiest way to pull your disks in to a VSAN datastore if you ask me.

Virtual SAN RAID 0 means that in order to use the disks you will need to create a single disk RAID 0 set for each disk in your system. The downside is when using this that things like hot-swap will be impossible as your Disk (ID) is bound to the RAID 0 set. However there is also a positive thing, many of these disk controllers support things like encryption of data at rest and if your disks support this you could potentially use this. It should be noted however that as far as I know today this functionality has not been tested (extensively) and support could be an issue. However, I could see why one would want to buy a controller that offer this functionality to be future proof.

Then there is another aspect, I have been asked about this a couple of times already and that is the performance capability of the controller. As far as I have seen the HCL today consists of 3Gbps and 6Gbps controllers. In most cases there is little to no cost difference, so if supported I would always recommend to go with the faster controller. But there is another thing here that is often overlooked and that is the queue depth. Before you pull the trigger and decide to buy controller-A over controller-B you may want to verify what the queue depth is of both of them. In some cases, and especially the cheaper disk controllers, the queue depth is low (32) where others offer 256 and higher. Especially when you are building an environment where a lot of IO is expected these are things to take in to consideration, plus you wouldn’t want to buy a screaming fast SSD and then find out your bottleneck is the queue depth of your disk controller right?

<update>A very good point made by Tom Fenton, if you select a controller and are at the point of rolling out VSAN make sure you validate the firmware and the driver used. If you click on the “Model” you will be able to see those details. This also applies for SSDs and HDDs!</update>

I hope that helps,

Book: Networking for VMware Administrators

Fellow blogger Chris Wahl just announced the availability of an awesome book titled Networking for VMware Administrators he authored with Steve Pantol. The book is published via VMware Press and is a must read if you ask me. I am going to order it for sure as it is an area that I can definitely brush up on. The book is 368 pages and covers everything from the networking models to switching, but of course heavily focuses on the virtual side and dives in to the standard vSwitch, distributed switch and the Cisco Nexus 1000v!

Knowing Chris this book is going to be worth it, his blog material has always been excellent and I expect nothing less. Congrats Chris and Steve, awesome work and looking forward to reading it.

You can pick the book up here: paper | kindle

Startup News Flash part 15

Number 15 of the Startup News Flash… What happened in the world of (storage / flash related) startup’s in the last couple of weeks? Not too much news, but I felt it was worth releasing anyway as other wise the below would be really old news.

One of the most interesting BC/DR startups of the last couple of years, if you ask me, just announced a new round of funding: 100 million. Investors include North Bridge, Greylock, Advanced Technology Ventures, Andreessen Horowitz, and Technology Crossover Ventures. For those who don’t know Actifio… Actifio offers what is commonly referred to as a “Data Copy Management” solution. It could be described as a solution which sits in between your storage solution and your hypervisor and can do things like: backup, cloning, replication, archiving etc. Really neat solution, with a brilliant super simple UI. Worth checking out if you are looking to improve your business continuity story!

A while back I wrote an introduction to SoftNAS. When doing that review there was one thing that stood out to me and that was that SoftNAS didn’t have a great availability story. I spoke with Rick Brady about that and he said that it would be one of the first things they would try to tackle in an upcoming release. In the just announced release SoftNAS introduces Snap HA. Snap HA provides an “active / passive” solution where when an issue arises ownership is transferred to the “passive” node which then of course becomes “active”. More details can be found in this blog post by Rick Brady. Awesome work guys!