Cloud | SIOS SANless clusters

How To Choose A Cloud When You Need High Availability

January 8, 2021 by Jason Aw Leave a Comment

How To Choose A Cloud When You Need High Availability

Understand the cloud market

A number of analyst firms are predicting an ever-increasing number of deployments of applications, databases, and solutions in the cloud. According to Gartner, firms are “moving to the cloud at an increasing rate.”^[1] In fact, Gartner and other analysts expect the pace of cloud migration and deployment will continue to accelerate, driven in large part by the pace of innovation in the cloud. In a TechTarget article by Kurt Marko, of MarkoInsights, Marko notes that the pace of innovation that is “being undertaken in the cloud likely can’t be replicated on premises due to the elastic, scalable, and on-demand nature of managed public cloud services.”

We see more and more companies that had been using the cloud only for DevOps applications and databases that were not essential to their business, are now moving mission-critical applications, ERPs and databases that require high availability protection to the cloud.

If you are considering a move to the cloud – and it seems likely that you are – there are several keys to understand when you need high availability.

Familiarize yourself with the cloud high availability options

To plan for the proper availability solution for a cloud or hybrid cloud deployment, consider what the pain points are with regards to both availability (99.9% uptime) and high availability (99.99% uptime). You also need to understand the options that are available for high availability with an eye towards your plans to migrate to the cloud. Notable analysts and experts suggest looking for solutions that will not only mitigate and reduce the pain of migrating your workloads, but will also provide a balanced and comprehensive approach to availability throughout the lifespan of your cloud architecture. Note, it is also wise to consider solutions that can provide protection and high availability for portions of your workload that may one day repatriate from the cloud back to your on-premises environment.

Here are ten things to consider when comparing your availability options in the cloud:

1. The deployment method. Is it possible to deploy the availability solution you are considering using an image, CLI, UI, or other repeatable solution such as cloud formation template or packaged scripts.

2. The system requirements. Most notably, consider the operating system (OS), disk, CPU, and memory requirements.

3. The deployment environments. Do your availability options support on-premises only, one or more public clouds, or can they support a mixture, and/or hybrid cloud deployment. Is there a SaaS offering available as well?

4. The breadth and depth of application protection. “Breadth” meaning what types of applications, databases, front-ends, networking, and infrastructure components can be protected? Is there a flexible framework for adding new applications and variants? “Depth” meaning – is the solution application-aware – and able to maintain application-specific best practices throughout the application failover/failback processes?

5. Performance requirements. We often think of RTO and RPO, but what about other performance needs of your solution. Will your availability solution cause performance issues on failover?

6. Resilience requirements. How large a cluster can the availability solution support?, How many faults and failures can it detect and recover from. How will replication be handled while keeping metadata in sync?

7. Supportability and maintenance. Does the availability vendor have experience with a wide range of availability needs and configurations? Do they have longevity, and a support system designed to address issues that may go beyond their solution? Can they help you minimize disruption and planned downtime during your system management and maintenance (patches, upgrades, and general maintenance).

8. Total cost of ownership. There are entire industries and services dedicated to helping you calculate the total cost of ownership, so we won’t cover that here. Suffice it to say, your calculations will be unique to your organization, cloud provider, applications, and IT team. You should consider whether your availability solution vendor can help you identify strategies for saving utilization, licensing, and other costs? Does the solution automate manual tasks, reduce IT labor time?

9. Licensing and pricing model. How do you consume the cost of the software? Is there a subscription fee, subscription model, pay-as-you-go offering, bring your own license (BYOL), or combination of flexible options. How will you enable the product licensing? Is there a license server, licensing service, or encrypted key based on virtual machine deployment details, such as address, hostname, MAC address.

10. The impact on IT staff. How much training with the solution require? How much manual intervention will be needed in the event of an application failure event or disaster? Will it require specialized scripting that needs to be maintained? Who will be responsible for ongoing maintenance?

Weigh the benefits and trade-offs

Like every important decision, you need to understand your tradeoffs and choose the best balance to meet your needs. For example, I recently asked a friend to recommend a good walking shoe. I bought a pair he raved about – noting how lightweight they were, how strong and durable the fabric, and how stylish they were. I went for my first long walk-run in them, and I donated my first pair of “one run” shoes immediately thereafter. When I went to ‘Fleet Feet’ to get an expert’s opinion I ended up with a heavier shoe, with more breathable fabric (also less durable), and an unrivaled level of hideousness. I made a tradeoff between appearance and function that worked for my needs and budget.

Like running shoes, there is no silver bullet solution that will be the right fit for every company, every application, every database, and every possible server and architecture. You are officially free to stop looking for it. Instead, settle into the activity of weighing the trade-offs to determine what is the right fit for your company’s needs. Think about your tradeoffs. For example, if you’re sure you will be a full Microsoft shop, the importance of GCP and AWS support should be a little lower in your evaluation process.

Take your IT infrastructure dynamics into account

Think holistically about availability in your entire IT infrastructure – both on premises and in the cloud. The reasons to do so are best explained with another analogy. In 2018, I was the coordinator for an outreach program feeding the homeless and hungry in Columbia, South Carolina. Our group met once a week to serve a meal and a message of hope to over 100 men, women and children. When we considered expanding – adding more days of the week, more hours, or additional services, we had to think well beyond simple scheduling requirements. Knowing that we were providing a critical service to clients who depend on us, we had to consider all the factors that affected our ability to deliver those services consistently for the long-term, such as: cost, ages of our team members, outside obligations, alternative methods to achieve our goals, risk factors, and other dynamics within our parent organization.

When you are choosing your solution, after you’ve understood the market, familiarized yourself with options, and weighed the trade-offs, the last step is to take into account the various other dynamics in your overall environment. Will the solution meet the needs of your business as a whole? Will your critical data be protected from loss? Will your end-user productivity be protected from downtime? What training will be required to move to the cloud and how will that impact your ability to manage or maintain the solution that you choose? What IT roles will be added, removed, or changed in your cloud journey? Will any responsibilities for application availability move to any line-of-business owners? And how will the shifts in responsibilities, or team make up improve or decrease your overall potential for success. Consider whether your team needs to take a step-by-step approach, migrating smaller workloads first.

As VP of Customer Experience, I have seen a wide range of cloud migrating planning – some straightforward others extremely disruptive. In one instance a customers’ move to the cloud was highly contentious because management saw it as an opportunity to eliminate an entire IT department. I’m not suggesting that you play politics, but you should be aware of all of the factors at play in these complex projects.

Migrating to the cloud is supposed to save money, time and resources while affording improvements in availability and resilience. Regardless of which cloud you choose, make sure that you consider these tips and select the corresponding availability solution that gives you the flexibility to deliver the protection you need in the configuration you want.

Learn more about cloud high availability options with SIOS.

– Cassius Rhue, VP of Customer Experience, SIOS

Reproduced with permission from SIOS

Six Reasons Your Cloud Migration Has Stalled

December 22, 2020 by Jason Aw Leave a Comment

Six Reasons Your Cloud Migration Has Stalled

More and more customers are seeking to take advantage of the flexibility, scalability and performance of the cloud. As the number of applications, solutions, customers, and partners making the shift increases, be sure that your migration doesn’t stall.

Avoid the Following Six Reasons Cloud Migrations Stall

1. Incomplete cloud migration project plans

Project planning is widely thought to be a key contributor to project success. The planning plays an essential role in helping guide stakeholders, diverse implementation teams, and partners through the project phases. Planning helps identify desired goals, align resources and teams to those goals, reduce risks, avoid missed deadlines, and ultimately deliver a highly available solution in the cloud. Incomplete plans and incomplete planning are often a big cause of stalled projects. At the ninth hour a key dependency is identified. During an unexpected server reboot an application monitoring and HA hole is identified (see below). Be sure that your cloud migration has a plan, and work the plan.

2. Over-engineering on-premises

“This is how we did it on our on-premises nodes,” was the phrase that started a recent customer conversation. The customer engaged with Edmond Melkomian, Project Manager for SIOS Professional Services, when their attempts to migrate to the cloud stalled. During a discovery session, Edmond was able to uncover a number of over-engineered items related to on-premises versus cloud architecture. For some projects, reproducing what was done on premises can be a resume for bloat, complexity, and delays. Analyze your architecture and migration plans and ruthlessly eliminate over-engineered components and designs, especially with networking and storage.

3. Under-provisioning

Controlling cost and preventing sprawl are an important and critical aspect of cloud migrations. However, some customers, anxious about per hour charges and associated costs for disks and bandwidth fall into the trap of under-provisioning. In this trap, resources are improperly sized, be that disks that have the wrong speed characteristics, compute resources with the wrong CPU or memory footprint, or clusters with the wrong number of nodes. In such under-provisioned cases, issues arise when User Acceptance Test (UAT) begins and expected/anticipated workloads create a log jam on undersized resources. Or a cost optimization of a target node is unable to properly handle resources in a failover scenario. While resizing virtual machines in the cloud is a simple process, these sizing issues often create delays while architects and Chief Financial Officers try to understand the impact of re-provisioning resources.

4. Internal IT processes

Every great enterprise company has a set of internal processes, and chances are your team and company are no exception. IT processes are usually key among the processes that can have a large impact on the success of your cloud migration strategy. In the past, many companies had long requisition and acquisition processes, including bids, sizing guides, order approvals, server prep and configuration, and final deployment. The cloud process has dramatically altered the way compute, storage, and network resources, among others, are acquired and deployed. However, if your processes haven’t kept up with the speed of the cloud your migration may hit a snag when plans change.

5. Poor High Availability planning

Another reason that cloud migrations can stall involves high availability planning. High availability requires more than a bundle of tools or enterprise licenses. HA requires a careful, thorough and thoughtful system design. When deploying an HA solution your plan will need to consider capacity, redundancy, and the requirements for recovery and correction. With a plan, requirements are properly identified, solutions proposed, risks thought through, and dependencies for deployment and validation managed. Without a plan, the project and deployment are vulnerable to risks, single point of failure issues, poor fit, and missing layers and levels of application protection or recovery strategies. Often when there has been a lack of HA planning, projects stall while the requirements are sorted out.

6. Incomplete or invalid testing

Ron, a partner migrating his end customer to the cloud, planned to go-live over an upcoming three day weekend. The last decision point for ‘go/no-go’ was a batch of user acceptance testing on the staging servers. The first test failed. In order to make up for lost time due to other migration snags, Ron and team skipped over a number of test cases related to integrating the final collection of security and backup software on the latest OS with supporting patches. The simulated load, the first on the newly minted servers, tripped a series of issues within Ron’s architecture including a kernel bug, a CPU and memory provisioning issue, and storage layout and capacity issues. The project was delayed for more than four weeks to address customer confidence, proper testing and validation, resizing and architecture, and apply software and OS fixes.

The promises of the cloud are enticing, and a well planned cloud migration will position you and your team to take advantage of these benefits. Whether you are beginning or in the middle of a cloud migration, we hope this article helps you be more aware of common pitfalls so you can hopefully avoid them.

– Cassius Rhue, Vice President, Customer Experience

Reproduced from SIOS

Calculating Application Availability In The Cloud

December 18, 2020 by Jason Aw Leave a Comment

Calculating Application Availability In The Cloud

When deploying business critical applications in the cloud, you want to make sure they are highly available. The good news is that if you plan properly, you can achieve 99.99% (4-nines) of availability or more. However, calculating your true availability may not be as straightforward as it seems.

When considering availability, you must consider the key components that make access to your application possible, which I’ll call the availability chain. Component of the availability chain are:

Compute
Network
Storage
Application
Dependent services

Your application is only as available as your weakest link, and your downtime increases exponentially with each additional link you add to the chain. Let’s examine each of the links.

Compute Availability

Each of the three major cloud service providers have some similarities. One thing in common across all three platforms is the service level agreements (SLA) they will commit to for compute.

The SLA for all three public cloud providers for VMs when you have two or more VMs configured across different availability zones is 99.99%. Keep in mind, this SLA only guarantees the remote accessibility of one of the VMs at any given time, it makes no promises as to the availability of the services or application(s) running inside the VM. If you deploy a single VM within a single datacenter, this SLA varies from “90% of each hour” (AWS) to 99.5% (Azure and GCP) or 99.9% (Azure single VM when using Premium SSD).

True high availability starts at 99.99%, so the first step is to ensure your application is available is to make sure the application is distributed across two or more VMs that span availability zones. With two VMs spread across two availability zones, giving you 99.99% availability of at least one of those VMs, you could theorize that if you had three VMs spread across three availability zones your availability would be even greater than 99.99%. Although the cloud providers’ SLA will never guarantee beyond 99.99% availability regardless of the number of availability zones in use, if you use pure statistics you might come to the conclusion that your availability could jump to as high as 99.999999% or 8-nines of availability, 26.30 milliseconds downtime per month.

1-(.0001*.0001) = .99999999

99.999999% availability with three availability zones?

Don’t go around quoting that number. But just keep in mind that it makes sense that if two availability zones can give you 99.99% availability. It stands to reason that three availability zones is going to give you something significantly more than 99.99% availability.

Compute is just one link in the availability chain. We still have to address network, storage and other dependent services, which all represent possible points of failure.

Network Availability

In order for your application to be available, every network hop between the client and the application and all the resources that the application depends on, must be available and working within tolerable latency ranges. You need to understand the network links between database servers, application servers, web servers and clients to know precisely where the network might fail. Remember, the more links in your availability chain the lower your overall availability will be.

Although network availability betweens VMs in the same vNet are covered under the standard compute SLA, there are other network services that you may be utilizing. Here are just a few examples of network services you could be utilizing which would impact overall application availability.

Express Route – 99.95%
VPN Gateway – 99.9% through 99.95%
Load Balancer – 99.99%
Traffic Manager – 99.99%
Elastic Load Balancer – 99.99%
Direct Connect – 99.9% – 99.99%

Building on what we have learned so far, let’s take a look at the availability of an application that is deployed across two availability zones.

99.99% compute availability

99.99% load balancer availability

.9999 * .9999 = .9998

99.98% availability = ~9 minutes downtime per month

Now that we have addressed compute and network availability, let’s move on to storage.

Storage Availability

Now here is where the story gets a little hairy. Have a look at the following storage SLAs

https://azure.microsoft.com/en-us/support/legal/sla/storage/v1_5/

https://cloud.google.com/storage/sla

https://aws.amazon.com/compute/sla/

It seems pretty clear that Azure and Google are giving you a 99.9% SLA on block storage solutions. AWS doesn’t mention EBS specifically here. They only talk about VMs and measure their single instance VMs availability by the hour instead of by the month as the other cloud providers do. For sake of discussion, lets use the 99.9% availability guarantee that both Azure and GCP have published.

Building upon our previous example, let’s add some storage to the equation.

99.99% compute availability

99.99% load balancer availability

99.9% managed disk

.9999 * .9999 * .999 = .9988

99.88% availability = ~53 minutes of downtime per month.

53 minutes of downtime is a lot more than the 9 minutes of downtime we calculated in our previous example. What can we do to minimize the impact of the 99.9% storage availability? We have to build more redundancy in the storage!

Fortunately, we usually include storage redundancy when planning for application availability. For instance, when we stand up web servers, each web server will typically store data on the locally attached disk. When deploying domain controllers, Microsoft Active Directory takes care of replicating AD information across all the domain controllers. In the case of something like SQL Server, we leverage things Always On Availability Groups or SIOS DataKeeper to keep the data in sync across locally attached disks.

The more copies of the data we have distributed across different availability zones, the more likely we will be able to survive a failure.

For example, an application that stores its data across two different disks in different availability zones will benefit from the redundancy and instead of 99.9% availability it is more likely to achieve 99.9999% availability of the storage.

1 – (.001 * .001) = .999999

If we throw that into the previous equation, the picture starts to look a little brighter.

.9999 * .9999 * .999999 = .9998

99.98% availability = ~9 minutes of downtime

By duplicating the data across multiple AZs, and therefore multiple disks, we have effectively mitigated the downtime associated with cloud storage.

Application And Dependent Services Availability

You’ve done all you can do to ensure compute, network, and storage availability. But what about the application itself? Some applications can scale out and provide redundancy by load balancing between multiple instances of the same application. Think of your typical web server farm where you may typically load balance web requests between five servers. If you lose one server, the load balancer simply removes it from its rotation until it is once again responsive.

Other applications require a little more care and monitoring. Take SQL Server for instance. Typically Always On Availability Groups or Failover Cluster Instances are used to monitor database availability and take recovery actions should a database become unresponsive due to application or system level failures. While there is no published SLA for SQL Server availability solutions, it is commonly accepted that when configured properly for high availability, a SQL Server can provide 99.99% availability.

You may rely on other cloud based services, like hosted Active Directory, hosted DNS, microservices, or even the availability of the cloud portal itself should all be factored into your overall availability equation.

Summary

Application availability is the sum of all the moving parts. Skimping in just one area can exponentially impact the overall availability of your application. Take your time and investigate all the links in your availability chain for weakness including compute, network, storage, application and dependent services.

In general the numbers presented here are hopefully worst case scenarios and your actual availability should exceed the published SLAs. Do your homework and be wary of any service that can not guarantee 99.99% availability, the typical threshold of what is considered highly available.

Human error and security were not addressed in this article. You can make your application as highly available as possible. However, if you have not taken steps to secure your application against external threats and stupid human mistakes then all bets are off when it comes to availability.

Lessons in Cloud High Availability from the Movies

August 11, 2020 by Jason Aw Leave a Comment

Lessons in Cloud High Availability from the Movies

Joseph Lalonde of jmlalonde.com has a blog highlighting the leadership lessons from popular movies such as Hancock, The Greatest Showman, and Frozen II. In credit to Joseph’s inspiring leadership lessons, here are four high availability lessons on cloud migration from Disney’s Frozen II.

Disney’s Frozen II and Cloud Migration Lessons

In Disney’s animated adventure Frozen II the characters Anna, Elsa, Kristoff, Olaf and Sven leave Arendelle to travel to an ancient, autumn-bound forest of an enchanted land. In the adventure, they set out to find the origin of Elsa’s powers in order to save their kingdom. Aside from being fun for a father of six girls, the movie is also ripe with leadership, life, and high availability lessons.

1. You can’t go into cloud migration without the proper help.

When Elsa, Anna, Kristoff, Olaf and Sven arrive at the place where the mysterious voice has been calling them, they stand outside an enormous cloud. When Olaf and Kristoff attempt to enter, they are bounced back and repelled. It is only when Elsa approaches the cloud with her magic that the portal opens and they enter.

When migrating to the cloud, there will be a lot of voices calling you. Some will beckon you to AWS, or Azure or GCP, or a myriad of others. But, no matter which you intend to go with, know that you will need the proper help for a successful entry. This help should include:

Architects knowledgeable of the platform, especially the networking aspects
Application administrators who understand the applications installation, configuration, operation and maintenance characteristics
Security and OS administrators
A cloud partner representative
A knowledgeable availability expert for deploying critical applications in highly available architecture

2. Things will not make sense when you are older, so document and iterate.

While walking through the enchanted forest, Olaf begins experiencing the strange phenomenon and magic of the forest. As he does, he begins to sing:

This will all make sense when I am older
Someday I will see that this makes sense
One day, when I’m old and wise
I’ll think back and realize
That these were all completely normal events
I’ll have all the answers when I’m older

The song concludes with the rousing finish of:

‘Cause when you’re older
Absolutely everything makes sense
This is fine

Stop. If things don’t make sense to you when you are starting out in your cloud journey, take the time to make them make sense. If you are using an agile mindset, launch an investigation spike on the singular topic or topics of confusion. For example, if you don’t understand the magic of the VPC, Security Group, Availability Zone or Set, Region, or Region to Region concepts today, they will make even less sense later down the road when you return to this configuration months later. If the test results don’t make sense, don’t move on, run them again. Also, remember to document the architecture, not just the details you think are important, but the details that the older you who have moved through six other projects and is facing a deadline would want to know to make it all make sense.

3. Don’t go running into the fire. Choose the right cloud high availability solution.

After a brush with the wind spirit, the enchanted forest is set ablaze by the fire spirit. As the fire spirit spreads chaos, and fire, Elsa charges off with icy blasts to cool the fire and calm this spirit. In her zeal, Anna runs into the fire behind her sister and has to be saved. When at last the two are reunited, Elsa admonishes her sister- “You can’t just follow me into fire”. The feisty Anna replies, “You don’t want me following you into fire? Then don’t run into fire!”

Migrating to the cloud and choosing the right availability solution for you can be stressful enough without complicating it by making unrealistic schedules with untested theories and scenarios. No leader of a deployment team wants his or her team in a fire drill, so don’t knowingly run into one. Create a plan. Establish checkpoints and milestones. Include realistic risk and risk management strategies. Communicate frequently with vendors and partners, and especially with your team. Test well, and understand backup and backout plans.

4. Don’t get stuck in the past re: what you bring in your cloud migration.

There is a song woven throughout the movie, “All is Found” with the chilling chorus – “Dive down deep into her sound / But not too far or you’ll be drowned.” Elsa dives down into the deep as the movie peaks and her search and exploration of the past leave her Frozen, her last gasp a burst of flurries to warn and inform her sister.

As one of the heads of our Customer Experience Team at SIOS Technology Corp., I have witnessed too many deployments and migrations get stuck in a comparison trap. The phrase goes like this, “In our old data center, we” or “The old system could do that.” It may be true that your old system of fixed systems, dedicated resources, large teams, specific networking, and high cost, high feature SAN storage could do that. (Although, truthfully, sometimes I’ve seen the curtain peeled back and on-premise didn’t really do that either). As you migrate to the cloud, understand what makes sense to mimic in the cloud and what doesn’t. Understand why the system was architected that way on-premises and using the help, “lesson 1, and the learning of lesson 2, make decisions that make sense.

Which leads me to the final lesson.

5. There will always be two kingdoms: on-premises and in the cloud.

At the end of the movie, Anna becomes queen of Arendelle once ruled by her sister Elsa, while Elsa stays and leads the people of the Northuldra. There is one who stays in or near the forest once surrounded by mystery and cloud, while the other returns to the familiar land.

As you consider migration to the cloud and your High Availability strategy, remember there will always be two kingdoms. Your migration strategy would do well to remember that you will always have a need for an on-premise data center to partner with your cloud deployments. Perhaps it isn’t as sprawling as it once was, but not every workload or critical infrastructure can be repurposed and packaged for the cloud. Having an HA solution and strategy that can equip and enable both “kingdoms” is essential.

Going to the cloud takes the right team, the right tools and the right solutions, and a strategy and plan to get there, without going through fire. As you migrate to the cloud, be willing to confront the past, understand it, and remember not to get stuck there. And, like the two sisters of Disney’s Frozen II, you’ll do well to remember every beautiful enterprise story has two sides, on-premise and cloud just might be yours.

— Cassius Rhue, VP, Customer Experience

Reproduced with permission from SIOS