VMware vLockstep: How to Increase FT of Your VMs

Out of the many features that VMware technology support, there is one which is really interesting and lesser known. It is called vLockstep, and it is a nice feature to increase the Fault-Tolerance of your machines.

Using modern technology doesn’t mean that our data-center is bulletproof, every technology has its own limits. VMware experts already know that if a physical host fails, the virtual machines can reboot on another host, so to limit your overall downtime. Nevertheless, what if your machines are in such a critical state that you can’t have this reboot time in the case of a host failure? The answer might be VMware Fault Tolerance (FT).

VMware Fault Tolerance provides continuous availability for virtual machines by creating and maintaining a Secondary VM that is identical to, and continuously available to replace, the Primary VM in the event of a fail-over situation. Read it as a ghost VM backing up your primary one covertly.

There is another proprietary patented algorithm that helps VMware achieve this unusual feature, that is the vLockstep technology we were talking about. Let’s deep dive into how vLockstep helps us to take advantage of fault tolerant VMs.

VMware vLockstep: How it Works

VMware vLockstep is a technology that captures inputs and events that occur on a primary virtual machine (VM) and sends them to a secondary VM. This supports VMware’s Fault Tolerance component of VMware vSphere.

VMware primary virtual machine sending to a secondary virtual machine

VMware’s Fault Tolerance works by keeping a primary virtual machine (VM) and a secondary VM in perfect sync. VMware vLockstep captures inputs and events that occur on the primary VM and sends them to the secondary VM. Because the secondary VM is always in sync with the primary VM, it can take over in the event of a primary VM failure without interruption and provide fault-tolerant protection. When the secondary VM takes over, VMware FT automatically creates a new secondary VM. In fact, the name “Lockstep” comes from a style of a military march that emphasizes synchronous movement.

For vLockstep to reproduce CPU instructions from the primary VM on the secondary VM, the Intel or AMD processors used must have the appropriate performance counter architecture and virtualization hardware assists. Both hosts supporting the VM pair must be in the same processor family.

VMware vLockstep should be set up on a dedicated network interface card (NIC) with at least 1 GB/s of throughput. Although all data is synchronized between the paired VMs over a server backbone network, outputs are suppressed in the secondary VM. For instance, VMware FT ensures only the primary VM initiates write operations to storage. Certain actions and instructions that are irrelevant for the secondary VM are not synced via vLockstep, reducing the burden on disk space and processors.

In versions of vSphere earlier than v.5, the vLockstep VM pairs were marked as “disabled” in VMware Distributed Resource Scheduler (DRS), enabling higher compatibility between VMware FT and DRS. In either case, users experience no interruption in service and no loss of data.

A fault tolerant virtual machine and its secondary copy are not allowed to run on the same host. This restriction ensures that a host failure cannot result in the loss of both virtual machines. You can also use VM-Host affinity rules to dictate which hosts designated virtual machines can run on. If you use these rules, be aware that for any Primary VM that is affected by such a rule, its associated Secondary VM is also affected. For more information about affinity rules, see the vSphere Resource Management documentation.

Fault Tolerance also avoids “split-brain” situations, which can lead to two active copies of a virtual machine after recovery from a failure. Atomic file locking on shared storage is used to coordinate fail-over so that only one side continues to run as the Primary VM and a new Secondary VM is re-spawned automatically.

How VMware vLockstep can help your organization

VMware vLockstep eliminates even the smallest of disruptions caused by server hardware failures. VMware Fault Tolerance provides instantaneous, non-disruptive fail-over in the event of server failures, protecting organizations from even the smallest disruptions or data losses when downtime costs can run into thousands of dollars in lost business.

It also provides continuous availability to any critical application. All applications that run inside a VMware virtual machine can be protected by VMware Fault Tolerance, allowing continuous levels of availability to be possible even for homegrown or custom applications. Automatic detection of failures and seamless fail-over ensure that applications continue to run without interruptions, user disconnects or data loss during hardware failures.

Finally, it delivers uninterrupted service with simplicity and low cost. VMware Fault Tolerance works with existing VMware High Availability (HA) or VMware Distributed Resource Scheduler (DRS) clusters and can be simply turned on or turned off for virtual machines. When applications require operational continuity during critical periods such as month end or quarter end time periods for financial applications, VMware Fault Tolerance can be turned on with the click of a button to provide extra assurance. The operational simplicity of VMware Fault Tolerance is matched by its low cost. In fact, it is simply included as a component in VMware vSphere and requires no specialized dedicated hardware.

Avatar

Written by

Prasoon Majumdar

An avid learner, technical evangelist and adventurous. I love to talk about scalability. Self-starter with a proven track record in systems administration, programming, security, networking, monitoring, scripting and automation.Exceptionally strong passions for Unix Systems, Coding and Automation.Strongly advocate standardization of technologies, automation, industry best practices, standard repeatable deployments, proactive monitoring and writing generic utilities and reusable code.


Related Posts

Valery Calderón Briz
Valery Calderón Briz
— October 22, 2019

How to Go Serverless Like a Pro

So, no servers? Yeah, I checked and there are definitely no servers. Well...the cloud service providers do need servers to host and run the code, but we don’t have to worry about it. Which operating system to use, how and when to run the instances, the scalability, and all the arch...

Read more
  • AWS
  • Lambda
  • Serverless
Avatar
Stuart Scott
— October 16, 2019

AWS Security: Bastion Host, NAT instances and VPC Peering

Effective security requires close control over your data and resources. Bastion hosts, NAT instances, and VPC peering can help you secure your AWS infrastructure. Welcome to part four of my AWS Security overview. In part three, we looked at network security at the subnet level. This ti...

Read more
  • AWS
Avatar
Sudhi Seshachala
— October 9, 2019

Top 13 Amazon Virtual Private Cloud (VPC) Best Practices

Amazon Virtual Private Cloud (VPC) brings a host of advantages to the table, including static private IP addresses, Elastic Network Interfaces, secure bastion host setup, DHCP options, Advanced Network Access Control, predictable internal IP ranges, VPN connectivity, movement of interna...

Read more
  • AWS
  • best practices
  • VPC
Avatar
Stuart Scott
— October 2, 2019

Big Changes to the AWS Certification Exams

With AWS re:Invent 2019 just around the corner, we can expect some early announcements to trickle through with upcoming features and services. However, AWS has just announced some big changes to their certification exams. So what’s changing and what’s new? There is a brand NEW ...

Read more
  • AWS
  • Certifications
Alisha Reyes
Alisha Reyes
— October 1, 2019

New on Cloud Academy: ITIL® 4, Microsoft 365 Tenant, Jenkins, TOGAF® 9.1, and more

At Cloud Academy, we're always striving to make improvements to our training platform. Based on your feedback, we released some new features to help make it easier for you to continue studying. These new features allow you to: Remove content from “Continue Studying” section Disc...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
  • ITIL® 4
  • Jenkins
  • Microsoft 365 Tenant
  • New content
  • Product Feature
  • Python programming
  • TOGAF® 9.1
Avatar
Stuart Scott
— September 27, 2019

AWS Security Groups: Instance Level Security

Instance security requires that you fully understand AWS security groups, along with patching responsibility, key pairs, and various tenancy options. As a precursor to this post, you should have a thorough understanding of the AWS Shared Responsibility Model before moving onto discussi...

Read more
  • AWS
  • instance security
  • Security
  • security groups
Avatar
Jeremy Cook
— September 17, 2019

Cloud Migration Risks & Benefits

If you’re like most businesses, you already have at least one workload running in the cloud. However, that doesn’t mean that cloud migration is right for everyone. While cloud environments are generally scalable, reliable, and highly available, those won’t be the only considerations dri...

Read more
  • AWS
  • Azure
  • Cloud Migration
Joe Nemer
Joe Nemer
— September 12, 2019

Real-Time Application Monitoring with Amazon Kinesis

Amazon Kinesis is a real-time data streaming service that makes it easy to collect, process, and analyze data so you can get quick insights and react as fast as possible to new information.  With Amazon Kinesis you can ingest real-time data such as application logs, website clickstre...

Read more
  • amazon kinesis
  • AWS
  • Stream Analytics
  • Streaming data
Joe Nemer
Joe Nemer
— September 6, 2019

Google Cloud Functions vs. AWS Lambda: The Fight for Serverless Cloud Domination

Serverless computing: What is it and why is it important? A quick background The general concept of serverless computing was introduced to the market by Amazon Web Services (AWS) around 2014 with the release of AWS Lambda. As we know, cloud computing has made it possible for users to ...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
Joe Nemer
Joe Nemer
— September 3, 2019

Google Vision vs. Amazon Rekognition: A Vendor-Neutral Comparison

Google Cloud Vision and Amazon Rekognition offer a broad spectrum of solutions, some of which are comparable in terms of functional details, quality, performance, and costs. This post is a fact-based comparative analysis on Google Vision vs. Amazon Rekognition and will focus on the tech...

Read more
  • Amazon Rekognition
  • AWS
  • Google Cloud Platform
  • Google Vision
Alisha Reyes
Alisha Reyes
— August 30, 2019

New on Cloud Academy: CISSP, AWS, Azure, & DevOps Labs, Python for Beginners, and more…

As Hurricane Dorian intensifies, it looks like Floridians across the entire state might have to hunker down for another big one. If you've gone through a hurricane, you know that preparing for one is no joke. You'll need a survival kit with plenty of water, flashlights, batteries, and n...

Read more
  • AWS
  • Azure
  • Google Cloud Platform
  • New content
  • Product Feature
  • Python programming
Joe Nemer
Joe Nemer
— August 27, 2019

Amazon Route 53: Why You Should Consider DNS Migration

What Amazon Route 53 brings to the DNS table Amazon Route 53 is a highly available and scalable Domain Name System (DNS) service offered by AWS. It is named by the TCP or UDP port 53, which is where DNS server requests are addressed. Like any DNS service, Route 53 handles domain regist...

Read more
  • Amazon
  • AWS
  • Cloud Migration
  • DNS
  • Route 53