Get rid of your unhealthy Azure instances

Have you ever had an Azure instance that just was not performing up to your expectations?

We have. And in the past, they were very hard to get rid of without affecting your entire cloud deployment.

How-To: Remove Azure instances that became slow or unhealthy

In this week’s How-To post, we’ll cover the new API that lets us easily remove an Azure instance that is performing poorly or has become unhealthy. We also share a tool we wrote to automate the removal, so you can remove dead Azure instances quickly whenever you need.

Read more: Azure: Remove unhealthy or slow role instances.

A bit of history

Back when we launched LeanSentry 2 years ago, we had a lot of issues with Azure instances not performing up to our expectations. In particular, the Azure host processes would die whenever the instances experienced high memory utilization from our custom cache layer, and begin to constantly recycle the role/reboot the VM. This caused service outages during times of peak usage.

Back then, the only way to take an instance out of rotation was to do VIP swap, or to scale down the service to a point where the offending instance would be removed (and so would all other instances with higher instance ids). Because we maintained a lot of in-memory and on-disk state on the instance, both of those options would be a huge no-no. So, we lobbied Microsoft to create an option to remove a specific instance, instead of trashing half of your service.

The Azure team came through and finally released an API to do this. This has been a godsend, allowing us to intelligently manage how we scale up and down so we can keep the instances with the highest efficiency / warmest cache.

For more on how to when to do this, and a tool to quickly delete instances, check out the How-To post here.

LeanSentry How-To: IIS & ASP.NET recommendations from our team

In the last 2 years, we’ve helped thousands of big and small companies to improve their IIS servers & ASP.NET applications.

Today, we are announcing LeanSentry How-To: a series of best-practice guides to help you solve common performance problems & improve your site health.

We’ll cover topics like:

1. Azure best practices
2. IIS & ASP.NET performance
3. Improving application & server stability
4. Advanced tools & techniques for troubleshooting production problems

To get these, sign up for our How-To series at LeanSentry How-To.

If you have specific areas or questions you would like to see covered, email us or post them here anytime.

Fix IIS & ASP.NET hangs faster with Hang diagnostics

Automatic hang diagnostics for IIS & ASP.NET apps has been one of LeanSentry’s most popular features.

Now, Hang diagnostics are getting even better, with more expert insight into hangs, better root cause detection, and more code-level data for your developers.

Automatically diagnose ASP.NET hangs

LeanSentry’s Hang diagnostics feature helps you resolve your website’s slowdowns, better than you can with generic monitoring tools. It does this by detecting and by automatically diagnosing dozens of common IIS, ASP.NET, and Classic ASP performance problems whenever your site experiences them.

No intrusive profilers, DebugDiag, or other tools needed. Like most of LeanSentry, hang diagnostics have virtually zero overhead during normal operation, and only a small overhead (5-10 seconds of analysis) when a problem is confirmed. This means you can add LeanSentry’s deep diagnostic insight to your existing monitoring without any conflicts or performance drops.

What’s new?

A lot! We’ve improved the diagnostic algorithms to detect more problems. Then there is the brand new diagnostic report interface that gives you better guidance, and more information on what caused the hangs.

See the actual IIS & ASP.NET operation

See the real request flow during ASP.NET hangs
See the actual request flow, and the key IIS & ASP.NET performance issues during the hang.

Expert guidance

Full ASP.NET hang analysis
LeanSentry analyzes the specific causes of the hang in your app, and gives you best practice guidance on how to address it.

Identify the function, slow SQL, REST call causing blocking

Diagnose ASP.NET hangs down to code, SQL query, and more
LeanSentry automatically determines the application code causing request blocking or thread pool exhaustion, and shows your the line of code, SQL query, REST url, or file being accessed.

Try it out

If you are still troubleshooting hangs the hard way, or trying to use the generic transaction monitoring tools, you are missing out. To learn more, check out LeanSentry’s hang diagnostics, and do a trial to see it for yourself.

LeanSentry is back, and better than ever!

You may have noticed that we’ve been very quiet in the last year.  The reason: as a small team, we found the initial demand for LeanSentry a bit overwhelming. This made it difficult to focus on building the kind of product we envisioned.

So, we decided to take a year to innovate our product, and deliver the kind of experience that our customers wanted.

Today, we are back with a brand new and whole new generation of our service.

What does LeanSentry do?

LeanSentry uses expert analysis techniques, many developed at Microsoft, to give you deeper insight into your web apps.

We automatically analyze IIS and ASP.NET performance, troubleshoot website hangs, tune .NET CPU and memory usage, troubleshoot errors, and much more.

The best part? It’s lightweight, cannot affect your applications, and can run alongside any existing APM or monitoring tool.

What’s different about LeanSentry?

In short, everything!

We have a brand new, real-time interface that makes it easy to access information with just a few clicks.

Our diagnostics have been upgraded to be way easier, and give you lot a lot more insight into your stack’s performance.

LeanSentry Dashboard
We have a simpler, faster deployment that lets you add LeanSentry to your production servers, Windows Azure or Amazon EC2 in less than 5 minutes, with no restarts or iisreset.

Here are some highlights for a quick glance:

Give me!

If you’ve tried LeanSentry a while back, you simply must see it again.

If you have not, this is a good time to check it out! Head over to and sign up for the free trial to see for yourself.

To all our customers and everyone that supported us so far, thank you! We hope the new service makes your life that much better. Stay tuned for a lot more about the new product, our story, and much more in the coming weeks!

What do IIS hangs, slow requests, errors, and high CPU have in common?

In the last several months, we’ve worked hard to provide automatic diagnostics for most application problems on the Microsoft web platform … hangs, request queuing, errors, high CPU, and so on.

Even though LeanSentry can automatically detect and and diagnoses many of these problems, it can sometimes it can be difficult to see how they all relate … and how they impact the overall health of your web application.

NEW: Alert layers!

Alert layers uses layers of bubbles to show you all your performance problems, and how they affect your application’s health … directly on the application’s health timeline!

Alert layers show you all the application problems and how they affect application health.


With these alert “bubbles”, you can instantly see where alerts took placehow they affected your request satisfaction in that moment, and how they related to other alerts.

This can often tell a more complete story then looking at each alert in isolation.

Usage tips: 
 1. Hover over any alert to show it on the graph. 
 2. Click the alert number to make the alert “sticky” so it does not go away when you hover over another one. Click again to hide it. 
 3. Hover over alert bubbles to see more information.
 4. Click a bubble to go to the alert page, and diagnose it!To check this out, simply log into your dashboard and pick an application.

More good stuff coming your way!

Next, we are working on improving our alert pages so they are easier to understand, and show you the problem diagnosis right away.
Watch for big improvements here next week!


The LeanSentry Team





AppliedInnovations customers use LeanSentry to prepare apps for the holiday season

AppliedInnovations, a leading Windows hosting provider, announced a partnership with LeanSentry to help customers get their Windows web apps ready for the holiday rush.

It did so after getting requests from its customers who have already been finding LeanSentry incredibly helpful.

Says Mayer Kahan, owner of Osgood Textiles at

“We are a .NET shop, troubleshooting bugs has always been a time consuming process of code review and digging through server logs.

LeanSentry finally allowed us to see in real time how our site is performing, providing a single platform for viewing our whole environment.

As a result, we improved site performance, and were able to be better informed about what is really going on with our physical environment.”

If you are an AppliedInnovations customer, it has never been a better time to try LeanSentry.

If not, you can get your trial account now at  If you are running an ecommerce site on the Windows platform, this just might be a smart move for the Black Friday/Chrismas season.

Read about how retailers are using LeanSentry to get ready for the peak shopping season.



New Performance page helps you track website CPU/Memory & slow requests

This week, we have another big improvement for you.

We completely remade our Performance page, and made it a lot easier to view your website performance data.

What’s there?

  • Slow requests tab shows you what operations caused slow requests to your site.
  • Resource use tab shows you the CPU, Memory, and Network usage by the website … compare it across all servers … and give you the diagnostic data to explain what caused the usage.

As a bonus, you can enable CPU profiling, Memory diagnostics, and slow operation tracking directly from the page.

Above all, the new interface is clean and wonderfully simple.

This is available immediately in your LeanSentry account! Just log in and go to the Performance page for any of your websites.

Don’t have an account? Get a trial account to see it for yourself.

We have more great stuff coming next week, so stay tuned!

Fix ASP.NET problems FAST with Troubleshooting Tasks!

Announcing Troubleshooting Tasks!

Tasks are simple, step-by-step wizards to help you fixing ASP.NET problems.

Our users wanted a simpler way to solve common problems without finding them in the LeanSentry dashboard. And that’s exactly what we built.

Here is a video of using the “Fix slow requests” troubleshooting task to quickly troubleshoot slow page loads:

This also leverages the new slow operation tracking feature we announced last week, which tells you what causes your slow requests by tracking the operations that slow them down.

We already have tasks for:

  1. Fix your top errors
  2. Troubleshoot slow requests

More tasks are coming over the next couple weeks.  Do you have a suggestion for a task you’d like to see? Let us know!


The LeanSentry Team