Uptime
Uptime Uptime is the period of time when a site performs well.

Uptime corresponds to the time when a site is accessible from the Internet. The opposite term - downtime - shows for how long a site has not been working during specified period of time. Usually uptime is measured in percents, and for period of time is choosen year. Percents over the year could be easily transformed into time values. Some typical values of uptime and corresponding period of unavailability during the year are shown here:

90% - 876 hours

99% - 87 hours, 36 minutes

99.9% - 8 hours, 45 minutes, 36 seconds

99.99% - 52 minutes, 34 seconds

So high uptime is really important. Even if it seems that 99% is pretty high value - it corresponds to several days of failure. If that happens in a row, many clients can be lost. Uptime value is usually guaranteed by web hosting, where the site is hosted. Website Monitoring may help you to increase the uptime and check if the value, declared by the hosting company, is real.

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  • CM.Glossary.Downtime
  • CM.Glossary.WebHosting
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Host-Tracker under Windows Azure

Those, who actively involved with the Web, should know HostTracker, a company from Ukraine, which has been supporting one of the leading global web monitoring services since 2004. Its goal is to monitor site health and accessibility in near-real-time access. Using alert message system, HostTracker allows to reduce downtimes, to improve quality of service for users, to quickly localize troubles...

​Those, who actively involved with the Web, should know HostTracker, a company from Ukraine, which has been supporting one of the leading global web monitoring services since 2004. Its goal is to monitor site health and accessibility in near-real-time access. Using alert message system, HostTracker allows to reduce downtimes, to improve quality of service for users, to quickly localize troubles, and etc.

Architecturally, HostTracker includes a server-based hub, acting both as a data collector and control center, and a series of software agents, launched in various regions – typically using the equipment operated by major providers, hosters and affiliates. The geographically distributed architecture provides common system reliability and also allows collecting data in terms of access speed, bandwidth and other key performance characteristics on regional level – a critically important feature for the international business.

The first version of HostTracker, which is still functioning and providing services for tens of thousands of customers, was Linux based. Today, it is supported by nine control servers, located and organized in two DPCs on collocation principle, and few dozens of agents. Considering that the final objective of web monitoring is focused on increasing the uptime of client-based web resources – whereas 95% of HostTracker customers were able to increase it up to 99% – then, performance and accessibility of the service itself are not just critical, but rather fundamental parameters that influence the whole business. Theoretically, HostTracker should demonstrate accessibility close to 100%. However, an extensive growth of the service made this task hard to solve.

HostTracker was facing constantly increasing network traffic – a problem for seamless operation of the service. Inability to add new control servers on-the-fly, difficulties when maintaining not uniform and multiple-aged hardware was another limiting factor. Moreover, the desire to develop the service through wider protocol and network service support was meeting certain obstacles. “Unfortunately, for Linux there was a limited choice of ready-to-use solutions and libraries, while inventing something completely new was difficult”, says Artem Prisyazhnyuk, HostTracker director. “We had an idea of reviewing the stack of technologies we used for a more sophisticated one and after taking a closer look at the .NET platform, its potential in terms of scalability and network support, I realized that was exactly the thing we had been looking for.”

It was sure that migrating to a completely different platform should be a complex task – the project extended over three years. However, it was like blessing in disguise: during this period, the world has seen the cloud computing that seemed an ideal tool for solving both the scalability problem and putting aside one’s own whole infrastructure. Besides, the PaaS model allowed to remove most of the effort in terms of administering the solution and to control the application as a self-contained entity, to the extent of complete automation, and thus, Windows Azure had in fact no alternatives.

As a result, the second version of HostTracker, commercial operation of which started in May 2012, is already functioning under Windows Azure. Its central ingredient is realized as Web Role and associated with SQL Azure Database – it provides external portal, analytics and report generation, control of monitoring applications. The latter are ensured with instances of Worker Role, which also use SQL Azure Database to store their data and to provide the service scalability depending on the network loading. Agents are functioning as they did before, with the viability of their transfer to Windows Azure being considered.
Now, HostTracker uses HTTP/HTTPS and ICMP protocols to monitor specific ports, including various methods (HEAD/POST/GET), and etc.
 



Alarm reporting is available via email, SMS and instant messages. The customer can receive reports with statistics about resources being controlled and their performances. You can spend only 6 minutes to make monitoring settings for five sites, while the average response time in case of failure is limited by a couple of minutes, and it takes 1-3 minutes more to inform the customer about the problem. Using this service, anyone can check any site, including access from various regions.

 As a result, if on the one side the transfer to the .NET platform itself gave us the potential to modernize HostTracker, to optimize the application architecture and realize new internal functions, then, on the other side, the migration to the cloud allowed to refuse from less important, though time consuming activities such as administering the solution, and, first of all, to reach necessary performance indicators. Microsoft, for all basic Windows Azure services, declares 99,9% accessibility and guarantees monthly refunds, should this indicator be lower. This creates a firm ground for operating such services like HostTracker, as the accessibility is the most critical parameter for these applications. Using the cloud infrastructure also provides a better protection for the service: unauthorized access to the application and many types of attacks are effectively excluded, while the data safety is ensured by triple reservation.

HostTracker received another advantage from abandoning its own infrastructure. The service’s performance characteristics are also rather critical, for they directly affect the failure reporting system operation. In this respect, Windows Azure is virtually a drainless source of computing power. This means that by timely starting additional monitoring instances you can support HostTracker functioning parameters on the necessary level. Moreover, the cloud environment is exactly what you need in order to make this process almost fully automatic, excluding further need for direct control.

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The main feature of HostTracker monitoring service is the regular checks of web sites with monitoring intervals from 1 minute. Moreover, the HostTracker’s dedicated global monitoring checkpoints network currently includes more than 140 servers all over the world.

The main feature of HostTracker monitoring service is the regular checks of websites with monitoring intervals from 1 minute. Moreover, the HostTracker’s dedicated global monitoring checkpoints network currently includes more than 140 servers all over the world.

Each test is simulating the visit of a real user. If this imaginary visitor is able to load the site – everything is ok, otherwise – the site is revised again by a certain algorithm (just to be sure). Then, if an error was identified, it is recorded in the database and the notification of unavailability is sent. This is the easiest way to check the site’s availability. If you are interested, HostTracker has a great deal of more sophisticated tests to offer.

Types of tools for web accessibility evaluation

Here are some quick checks you can start with immediately that will move your web site toward better accessibility. It is worth noting that these checks support different protocols.

For example:

  • HTTP - this is an ordinary request, which is obtained from the user's browser.
  • Ping – helps to test site or server network connectivity. 
  • TCP-port - tests the site-to-application connectivity.
  • Database Check - a health check which can ensure that the web server can connect to the database and can also help in monitoring of other vital features. For those seeking a possibility to check the data on the page, there is a content check function. In this case, the virtual client is not just logging in, but also looking for the presence or absence of certain words and phrases. This feature helps you to detect whether some important section of the text has been lost. Moreover, it helps you to spot any mistakes on the page at once.
  • With HostTracker service you can also monitor the response and loading time of your web site. Furthermore, the corresponding data is being written to the inspection logs.

Armed with all these tests, you’ll be eager to collect extensive and thorough information about your web site. You’ll be entitled to know when, why and how did your web site stop working. For example, when the network, server or web site itself are down. Moreover, by using HostTracker, you can immediately detect when web site performance goes down and omit causing any inconveniences for your users. Or even more – you can easily recognize when some data isn’t regularly retrieved from the database. All these tools can help you pinpoint and rectify performance and speed issues with any publicly available web site. It, definitely, saves your time! And, in this case, downtime is small.

Interesting fact:

Almost all HostTracker’s customers are eager to reach 99% or higher uptime. By the way, the data from this service could be a good support in your future confrontations with hosting partner. Truly, many HostTracker’s customers have found a reliable web hosting partner or made him fulfill all promises and commitments according to the contract.

  • HostTracker provides options for monitoring the domain and SSL certificate expiry dates. This problem seems to be handled easily, as the registrar sends alert notifications, but history provides plenty of notification neglect examples.  Dropping the domain name is a widely spread problem. Actually, Microsoft has encountered it twice.
  • Also HostTracker is one of the best resources that can help to find out if your IPs or domains are on some SPAM-database (so called DNSBL). Apparently, if it seems that you're engaged in spamming or other unwanted online behaviour, your IPs or domain could get blacklisted and blocked. The blacklist usually contains email servers suspected of spreading spam or servers that have been infested with some nasty malware etc. 

Most Internet service providers and web servers use these blacklists to detect IPs linked to computers with pervading spam or unwanted activity. And the problem is: you can be blacklisted accidentally and be unaware about it. If it happens, your rankings will go down or disappear entirely. You can be truly innocent of any deliberate wrongdoing and still be on the list. For example, if you share your web hosting with someone unreliable. With this monitoring function you can be always aware if your company’s domain name is blacklisted and be ready to deal with it. You're likely to come across contacting the list by email or passing through some sort of automatic procedures in order to prove that you are not a robot when you’ll be trying to get off a blacklist.

HostTracker service settings

All above-mentioned checks teem with the wide variety of options:

  • Maintenance planning and scheduling – allows you, for instance, not to catch the errors during the server upgrade period.
  • Checks from a particular location- as outlined above, there is a huge network of global monitoring checkpoints, and it is possible to choose only regions with potential clientele:

  • Delay alerts – this option will postpone alert notifications for a specified time span; manage notifications in line with the importance of issues; control the life cycle of both alerts and their notifications.

As regards alert notifications option, clients will find themselves spoiled for choice. HostTracker provides notifications via e-mail, SMS and, by extension, via Skype, Hangouts and voice call. The most striking one - POST request. There is a possibility to send a request to a specific web server (e.g. to restart the web site automatically).

HostTracker service has an API, which allows pieces of software to interact. It is considered as a contract provided by one piece of computer software to another.

The next HostTracker’s advantage is that the service doesn’t require a lot of system resources (e.g. installation any client software). Almost all features are operating using cloud services, and can be configured with only HostTracker’s web site tools. And service settings, definitely, won’t take much time!

Generally speaking, the service is still being developed, as well as, the monitoring network expands, new tools pop up and so on. Considering new tools, they are being developed in response to the requests made by clients. Please don’t hesitate to contact HostTracker’s admins if you have any further suggestions about extra tools which yet aren’t provided by the service.

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