Welcome!

Apache Authors: Carmen Gonzalez, Liz McMillan, Elizabeth White, Pat Romanski, Christopher Harrold

Related Topics: Recurring Revenue, Industrial IoT, Linux Containers, @CloudExpo, Apache, @DevOpsSummit

Recurring Revenue: Blog Feed Post

Surviving a Datacenter Outage By @PagerDuty | @DevOpsSummit [#DevOps]

Unlike some companies that are using Cassandra to support their big data efforts, our data set is relatively small

Surviving a Datacenter Outage

By Amanda Folson

PagerDuty was built around one simple idea: waking up the right people when things break. When an event is triggered, PagerDuty makes magic to notify the right person or team that something is wrong.

However, ensuring that the message makes it out of our pipeline to you isn’t so simple. Because we’re providing notifications when your systems are down, there’s a pretty big constraint on us to be up. If you can’t trust us, who can you trust?

We rely on a few distributed technologies in our alerting pipeline because they offer us the redundancy we need to ensure alerts make it to users. We’ve spent a lot of time architecting our infrastructure to be as fault-tolerant as possible in order to provide durable and consistent read/write operations in our critical alerting pipeline.

pd-overview

This pipeline starts with an event endpoint — either HTTP or email. From there, each event from a customer’s monitoring tool goes through a pipeline of separate services (such as incident management and notification management services) and ultimately ends up at the messaging service that actually reaches out to people. Many of these services are built on Scala and supported by Cassandra on the back end for data storage. We also make use of other technologies such as Zookeeper for coordination. This pipeline must always be up and healthy so we can ensure notifications are reaching people.

Cassandra at PagerDuty

We’ve had Cassandra in production for about two and a half years. Unlike some companies that are using Cassandra to support their “big data” efforts, our data set is relatively small — in the order of 10s of GB at any given moment. Since we’re using it to usher events through our pipeline, once the event reaches the end the data about it can be purged from the pipeline. We aim to keep our dataset as slim as possible.

pdeventtimeline

Cluster Configuration

We typically create clusters of 5 Cassandra nodes, with a replication factor of 5. These nodes are split across three datacenters; two nodes in one, two nodes in another, and one node in yet another facility. We make use of Cassandra’s quorum consistency level in order to provide us with the durability we need in the pipeline. This means that every write must be written to a majority of the cluster i.e. at least 3 of the 5 nodes.

cassandracluster

This pattern isn’t without its flaws. Every operation is across the WAN and takes an inter-DC latency hit. In some ways, this runs counter to typical recommendations for database clusters. However, since this latency hit is not exposed to humans, we’re willing to live with this tradeoff given the benefits: events aren’t lost, messages aren’t repeated, and we get durability and availability in the event that we lose an entire datacenter. With this 3 of 5 pattern, everything is written to at least two datacenters.

How do we know this works?

We intentionally introduce failures into our infrastructure to make sure that everything continues to run smoothly in the event of an outage. This includes thoroughly testing Cassandra nodes in degraded and non-functional states. For more about this, see our Failure Friday post.

At PagerDuty, we like to solve interesting technical problems. If you’re interested in making our cluster more robust, we’re currently hiring for positions in San Francisco and Toronto.

The post Surviving a Datacenter Outage appeared first on PagerDuty.

Read the original blog entry...

More Stories By PagerDuty Blog

PagerDuty’s operations performance platform helps companies increase reliability. By connecting people, systems and data in a single view, PagerDuty delivers visibility and actionable intelligence across global operations for effective incident resolution management. PagerDuty has over 100 platform partners, and is trusted by Fortune 500 companies and startups alike, including Microsoft, National Instruments, Electronic Arts, Adobe, Rackspace, Etsy, Square and Github.

IoT & Smart Cities Stories
The platform combines the strengths of Singtel's extensive, intelligent network capabilities with Microsoft's cloud expertise to create a unique solution that sets new standards for IoT applications," said Mr Diomedes Kastanis, Head of IoT at Singtel. "Our solution provides speed, transparency and flexibility, paving the way for a more pervasive use of IoT to accelerate enterprises' digitalisation efforts. AI-powered intelligent connectivity over Microsoft Azure will be the fastest connected pat...
There are many examples of disruption in consumer space – Uber disrupting the cab industry, Airbnb disrupting the hospitality industry and so on; but have you wondered who is disrupting support and operations? AISERA helps make businesses and customers successful by offering consumer-like user experience for support and operations. We have built the world’s first AI-driven IT / HR / Cloud / Customer Support and Operations solution.
Codete accelerates their clients growth through technological expertise and experience. Codite team works with organizations to meet the challenges that digitalization presents. Their clients include digital start-ups as well as established enterprises in the IT industry. To stay competitive in a highly innovative IT industry, strong R&D departments and bold spin-off initiatives is a must. Codete Data Science and Software Architects teams help corporate clients to stay up to date with the mod...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...
Druva is the global leader in Cloud Data Protection and Management, delivering the industry's first data management-as-a-service solution that aggregates data from endpoints, servers and cloud applications and leverages the public cloud to offer a single pane of glass to enable data protection, governance and intelligence-dramatically increasing the availability and visibility of business critical information, while reducing the risk, cost and complexity of managing and protecting it. Druva's...
BMC has unmatched experience in IT management, supporting 92 of the Forbes Global 100, and earning recognition as an ITSM Gartner Magic Quadrant Leader for five years running. Our solutions offer speed, agility, and efficiency to tackle business challenges in the areas of service management, automation, operations, and the mainframe.
The Jevons Paradox suggests that when technological advances increase efficiency of a resource, it results in an overall increase in consumption. Writing on the increased use of coal as a result of technological improvements, 19th-century economist William Stanley Jevons found that these improvements led to the development of new ways to utilize coal. In his session at 19th Cloud Expo, Mark Thiele, Chief Strategy Officer for Apcera, compared the Jevons Paradox to modern-day enterprise IT, examin...
With 10 simultaneous tracks, keynotes, general sessions and targeted breakout classes, @CloudEXPO and DXWorldEXPO are two of the most important technology events of the year. Since its launch over eight years ago, @CloudEXPO and DXWorldEXPO have presented a rock star faculty as well as showcased hundreds of sponsors and exhibitors! In this blog post, we provide 7 tips on how, as part of our world-class faculty, you can deliver one of the most popular sessions at our events. But before reading...
DSR is a supplier of project management, consultancy services and IT solutions that increase effectiveness of a company's operations in the production sector. The company combines in-depth knowledge of international companies with expert knowledge utilising IT tools that support manufacturing and distribution processes. DSR ensures optimization and integration of internal processes which is necessary for companies to grow rapidly. The rapid growth is possible thanks, to specialized services an...
At CloudEXPO Silicon Valley, June 24-26, 2019, Digital Transformation (DX) is a major focus with expanded DevOpsSUMMIT and FinTechEXPO programs within the DXWorldEXPO agenda. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive over the long term. A total of 88% of Fortune 500 companies from a generation ago are now out of business. Only 12% still survive. Similar percentages are found throug...