DRS rules still active when DRS disabled?

I just received a question around DRS rules and why they are still active when DRS is disabled. I was under the impression this was something I already blogged about, but I cannot find it. I know some others did, but they reported this behaviour as a bug… which it isn’t actually.

Below is a screenshot of the VM/Host Rules screen for vSphere 6.0, it allows you to create rules for clusters… Now note I said “clusters” not DRS in specific. In 6.0 the wording in the UI has changed to align with the functionality vSphere offers. These are not DRS rules, but rather cluster rules. Whether you use HA or DRS, these rules can be used when either of the two is configured.

Note that not all types of rules will automatically be respected by vSphere HA. One thing which you can now also do in the UI is specify if HA should ignore or respect rules, very useful if you ask me and makes life a bit easier:

Startup intro: Rubrik. Backup and recovery redefined

Some of you may have seen the article by The Register last week about this new startup called Rubrik. Rubrik just announced what they are working on and announced their funding at the same time:

Rubrik, Inc. today announced that it has received $10 million in Series A funding and launched its Early Access Program for the Rubrik Converged Data Management platform. Rubrik offers live data access for recovery and application development by fusing enterprise data management with web-scale IT, and eliminating backup software. This marks the end of a decade-long innovation drought in backup and recovery, the backbone of IT. Within minutes, businesses can manage the explosion of data across private and public clouds.

The Register made a comment, which I want to briefly touch on. They mentioned it was odd that a venture capitalist is now the CEO for a startup and how it normally is the person with the technical vision who heads up the company. I can’t agree more with The Register. For those who don’t know Rubrik and their CEO, the choice for Bipul Sinha may come as a surprise it may seem a bit odd. Then there are some who may say that it is a logical choice considering they are funded by Lightspeed… Truth of the matter is that Bipul Sinha is the person with the technical vision. I had the pleasure to see his vision evolve from a couple of scribbles on the whiteboard to what Rubrik is right now.

I still recall having a conversation with Bipul talking about the state of the “backup industry”, and I recall we agreed the different components of a datacenter had evolved over time but that the backup industry was still very much stuck in the old world. (We agreed backup and recovery solutions suck in most cases…) Back when we had this discussion there was nothing yet, no team, no name, just a vision. Knowing what is coming in the near future and knowing their vision I do think this quote from the press release embraces best what Rubrik is working on and it will do:

Today we are excited to announce the first act in our product journey. We have built a powerful time machine that delivers live data and seamless scale in a hybrid cloud environment. Businesses can now break the shackles of legacy and modernize their data infrastructure, unleashing significant cost savings and management efficiencies.

Of course Rubrik would not be possible without a very strong team of founding members. Arvind Jain, Arvind Nithrakashyap and Soham Mazumdar are probably the strongest co-founders one can wish. The engineering team has deep experience in building distributed systems, such as Google File System, Google Search, YouTube, Facebook Data Infrastructure, Amazon Infrastructure, and Data Domain File System. Expectations just raised a couple of notches right?!

I agree that even the statement above is still a bit fluffy so lets add some more details, what are they working on? Rubrik is working on a solution which combines backup software and a backup storage appliance in to a single solution and initially will target VMware environments. They are building (and I hate using this word) a hyperconverged backup solution and it will scale from 3 to 1000s of nodes. Note that this solution will be up and running in 15 minutes and includes the option to age out data to the public cloud. What impressed me most is that Rubrik can discover your datacenter without any agents, it scales-out in a fully automated fashion and will be capable of deduplicating / compressing data but also offer the ability to mount data instantly. All of this through a slick UI or you can leverage the REST APIs , fully programmable end-to-end.

I just went over “instant mount” quickly, but I want to point out that this is not just for “restoring VMs”. Considering the REST APIs you can also imagine that this would be a perfect solution to enable test/dev environments or running Tier 2/3 workloads. How valuable is it to have instant copies of your production data available and test your new code against production without any interruption to your current environment? To throw a buzzword in there: perfectly fit for a devops world and continuous development.

That is about all I can say for now unfortunately… For those who agree that backup/recovery has not evolved and are interested in a backup solution for tomorrow, there is an early access program and I urge you to sign up to learn more but also help shaping the product! The solution is targeting environments of 200 VMs and upwards, make sure you meet those requirements. Read more here and/or follow them on twitter (or Bipul).

Good luck Rubrik, I am sure this is going to be a great journey!

Get your download engines running, vSphere 6.0 is here!

Yes the day is finally there, vSphere 6.0 / SRM / VSAN (and more) finally available. So where do you find it? Well that is simple… here:

Have fun!

vSphere HA respecting VM-Host should rules?

A long time ago I authored this white paper around stretched clusters. During out testing the one thing where we felt HA was lacking was the fact that it would not respect VM-Host should rules. So if you had these configured in a cluster and a host would fail then VMs could be restarted on ANY given host in the cluster. The first time that DRS would then run it would move the VMs back to where they belong according to the configured VM-Host should rules.

I guess one of the reasons for this was the fact that originally the affinity and anti-affinity rules were designed to be DRS rules. Over time I guess we realized that these are not DRS rules but rather Cluster rules. Based on the findings we did when authoring the white paper we filed a bunch of feature requests and one of them just made vSphere 6.0. As of vSphere 6.0 it is possible to have vSphere HA respecting VM-Host should rules through the use of an advanced setting called “das.respectVmHostSoftAffinityRules”.

When “das.respectVmHostSoftAffinityRules” is configured then vSphere HA will try to respect the rule when it can. So if there are any hosts in the cluster which belong to the same VM-Host group then HA will restart the respective VM on that host. Of course as this is a “should rule” HA has the ability to ignore the rule when needed. You can imagine that there could be a scenario where none of the hosts in the VM-Host should rule is available, in that case HA will restart the VM on any other host in the cluster. Useful? Yes, I think so!

What’s new for HA in vSphere 6.0?

Instead of one generic post with a bunch of data I picked a couple of features and dug a little bit deeper, today I will be discussing what is new for HA in vSphere 6.0. Lets start with a list and then look at the features / enhancements individually:

  • Support for Virtual Volumes – With Virtual Volumes a new type of storage entity is introduced in vSphere 6.0.
  • VM Component Protection – This allows HA to respond to a scenario where the connection to the virtual machine’s datastore is impacted temporarily or permanently.
    • “Response for Datastore with All Paths Down”
    • “Response for Datastore with Permanent Device Loss”
  • Increased scale – Cluster limit has grown from 32 to 64 hosts and to a max of 8000 VMs per cluster
  • Registration of “HA Disabled” VMs on hosts after failure

Lets start with support for Virtual Volumes. It may sound like this is a given but as the whole concept of a VMFS volume no longer exists with Virtual Volumes and VMs have “virtual volumes” instead of VMDKs you can imagine that some work was needed to allow for HA to restart virtual machines stored on a VVOL enabled storage system.

VM Component Protection (VMCP) is in my opinion THE big thing that got added to vSphere HA. What this feature basically allows you to do is protect yourself against storage failures. There are two types of failures VMCP will respond to and those are PDL and APD. Before we look at some of the details, I want to point out that configuring is extremely simple… Just one tickbox to enable it.

HA in vSphere 6.0

In the case of a PDL (permanent device loss), this is something HA already was capable of doing when configured through the command line, a VM will be restarted instantly when a PDL signal is issued by the storage system. For an APD (all paths down) this is a bit different. A PDL more or less indicates that the storage device does not expect the device to return any time soon. An APD is more of an unknown situation, it may return… it may not… and no clue how long it takes. With vSphere 5.1 some changes were introduced to the way APD is handled by the hypervisor in this mechanism is leveraged by HA to allow for a response. (Cormac wrote an excellent post about this APD handling here.) When an APD occurs a timer starts. After 140 seconds the APD is declared and the device is marked as APD time out. When the 140 seconds has passed HA will start counting. The HA time out is 3 minutes. When the 3 minutes has passed HA can restart the virtual machine, but you can configure VMCP to respond differently if you want it to. You could for instance specify that events are issued that a PDL or APD has occurred. You can also specify how aggressively HA needs to try to restart VMs that are impacted by an APD. Note that aggressive / conservative refers to the likelihood of HA being able to restart VMs. When set to “conservative” HA will only restart the VM that is impacted by the APD if it knows another host can restart it. In the case of “aggressive” HA will try to restart the VM even if it doesn’t know the state of the other hosts, which could lead to a situation where your VM is not restarted as there is no host that has access to the datastore the VM is located on. It is also good to know that if the APD is lifted and access to the storage is restored during the total of roughly 5 minutes and 20 seconds it would take to reboot the VM, that HA will not do anything unless you explicitly configure it do so. This is where the “Response for APD recovery after APD timeout” comes in to play.

HA in vSphere 6.0

Increased scale is pretty straight forward, from 32 to 64 hosts and a total of 8000 VMs per cluster. I don’t know too many customers hitting this boundaries but I do come across a request like this occasionally. So if you want to grow your cluster, you can now do so. Do note that you may hit other limits like the LUN limit or the VM limit or…

Registration of HA Disabled VMs after a failure is a feature I have requested a long time ago. I am glad to see this made it in to the release. Basically when you have HA disabled on a specific VM this feature will make sure that the VM gets registered on another host after a failure. This will allow you to easily power-on that VM when needed without needed to manually re-register it yourself. Note, HA will not do a power-on of the VM but it will just register it for you.

That was it for now…