Tag Archives: failure

Why Dropbox didn’t have to fail

dropbox outage dec 2015

Dropbox is currently experiencing a *major* outage. See the dropbox status page to get an update.

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I’ve written about outages a lot before. Are these types of major failures avoidable? Can we build better, with redundant services so everything doesn’t fall over at once?

Here’s my take.

1. Browse only mode

The first thing Dropbox can do to be more resilient is to build a browsing only mode into the application. Often we hear about this option for performaing maintenance without downtime. But it’s even more important during a real outage like Dropbox is currently experiencing.

Not if but *when* it happens, you don’t have control over how long it lasts. So browsing only can provide you with real insurance.

For a site like Dropbox it would mean that the entire website is still up and operating. Customers can browse their documents, view listings of files & download those files. However they would not be able to *add* or change files during the outage. Thus only a very small segment of customers is interrupted, and it becomes a much smaller PR problem to manage.

Facebook has experienced outages of service. People hardly notice because they’ll often only see a message when they try to comment on someone’s wall post, send a message or upload a photo. The site is still operating, but not allowing changes. That’s what a browsing only mode affords you.

A browsing only mode can make a big difference, keeping most of the site up even when transactions or publish are blocked.

Drupal is an open source platform that powers big publishing sites like Adweek, hollywoodreporter.com & economist.com. It supports a browsing only mode out of the box. An outage like this one would only stop editors from publishing new stories temporarily. It would be a huge win to sites that get 50 to 100 million with-an-m visitors per month.

Also: Is Amazon too big to fail

2. Redundancy

There are lots of components to a web infrastructure. Two big ones are webservers & databases. Turns out Dropbox could make both tiers redundant. How do we do it?

On the database side, you can take advantage of Amazon’s RDS & either read-replicas or Multi-AZ. Each have different service characteristics, so you’ll need to evaluate your app to figure out what works best.

You can also host MySQL, Percona or Mariadb direclty on Amazon instances yourself & then use replication.

Using redundant components like placing webservers and databases in multiple regions, Dropbox could avoid a major outage like they’re experiencing this weekend.

Wondering about MySQL versus RDS? Here are some uses cases.

Now that you’re using multiple zones & regions for your database the hard work is completed. Webservers can be hosted in different regions easily, and don’t require complicated replication to do it.

Related: Are SQL databases dead?

3. Feature flags

On/off switches are something we’re all familiar with. We have them in the fuse box in our house or apartment. And you’ll also find a bigger larger shutoff in the basement.

Individual on/off switches are valuable because they allow us to disable inessential features. We can build them into heavier parts of a website, allowing us to shutdown features in an emergency. Host components in multiple availability zones for extra piece of mind.

Read: 5 Things toxic to scalability

4. Simian armies

Netflix has taken a more progressive & proactive approach to outages. They introduce their own! Yes that’s right they bake redundancy & automation right into all of their infrastructure, then have a loose canon piece of software called Chaos Monkey that periodically kills servers. Did I hear that right? Yep it actually nocks components offline, to actively test the system for resiliency.

Take a look at the Netflix blog for details on intentional load & stress testing.

Also: When hosting data on Amazon turns bloodsport

5. Multiple clouds

If all these suggestions aren’t enough for you, taking it further you could do what George Reese of enstratus recommends and use multiple cloud providers. Not being dependant on one company could help in many situations, not just the ones described here.

Basic Amazon EC2 best practices require building redundancy into your infrastructure. Virtual servers & on-demand components are even less reliable than commodity hardware we’re familiar with. Because of that, we must use Amazon’s automation to insure us against expected failure.

Also: Why I like Etsy’s site performance report

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Is AWS the patient that needs constant medication?

storm coming

I was just reading High Scalability about Why Swiftype moved off Amazon EC2 to Softlayer and saw great wins!

We’ve all heard by now how awesome the cloud is. Spinup infrastructure instantly. Just add water! No up front costs! Autoscale to meet seasonal application demands!

But less well known or even understood by most engineering teams are the seasonal weather patterns of the cloud environment itself!

Join 28,000 others and follow Sean Hull on twitter @hullsean.

Sure there are firms like Netflix, who have turned the fickle cloud into one of virtues & reliability. But most of the firms I work with everyday, have moved to Amazon as though it’s regular bare-metal. And encountered some real problems in the process.

1. Everyday hardware outages

Many of the firms I’ve seen hosted on AWS don’t realize the servers fail so often. Amazon actually choosing cheap commodity components as a cost-savings measure. The assumption is, resilience should be built into your infrastructure using devops practices & automation tools like Chef & Puppet.

The sad reality is most firms provision the usual way, through the dashboard, with no safety net.

Also: Is your cloud speeding for a scalability cliff

2. Ongoing network problems

Network latency is a big problem on Amazon. And it will affect you more. One reason is you’re most likely sitting on EBS as your storage. EBS? That’s elastic block storage, it’s Amazon’s NAS solution. Your little cheapo instance has to cross the network to get to storage. That *WILL* affect your performance.

If you’re not already doing so, please start using their most important & easily missed performance feature – provisioned IOPS.

Related: The chaos theory of cloud scalability

3. Hard to be as resilient as netflix

We’ve by now heard of firms such as Netflix building their Chaos Monkey to actively knock out servers, in effort to test their ability to self-healing infrastructure.

From what I’m seeing at startups, most have a bit of devops in place, a bit of automation, such as autoscaling around the webservers. But little in terms of cross-region deployments. What’s more their database tier is protected only by multi-az or just a read-replica or two. These are fine for what they are, but will require real intervention when (not if) the server fails.

I recommend building a browse-only mode for your application, to eliminate downtime in these cases.

Read: 8 questions to ask an aws expert

4. Provisioning isn’t your only problem

But the cloud gives me instant infrastructure. I can spinup servers & configure components through an API! Yes this is a major benefit of the cloud, compared to 1-2 hours in traditional environments like Softlayer or Rackspace. But you can also compare that with an outage every couple of years! Amazon’s hardware may fail a couple times a hear, more if you’re unlucky.

Meanwhile you’re going to deal with season weather problems *INSIDE* your datacenter. Think of these as swarms of customers invading your servers, like a DDOS attack, but self-inflicted.

Amazon is like a weak immune system attacking itself all the time, requiring constant medication to keep the host alive!

Also: 5 Things toxic to scalability

5. RDS is going to bite you

Besides all these other problems, I’m seeing more customers build their applications on the managed database solution MySQL RDS. I’ve found RDS terribly hard to manage. It introduces downtime at every turn, where standard MySQL would incur none.

In my experience Upgrading RDS is like a shit-storm that will not end!

Also: Does open source enable the cloud?

Get more. Grab our exclusive monthly Scalable Startups. We share tips and special content. Our latest Why I don’t work with recruiters

Agile – What is it and why is it important?

Agile software development seeks a more lightweight methodology of making changes and releases to software.  In the traditional, incremental approach, large pieces of software are written at once, and releases happen less frequently.  Once features are complete, the testing phase happens, and then deployment to production.  These releases can happen over many weeks in time, so turnaround for new features tends to be slow.   Advocates would argue that this forces discipline in the process, and prevents haphazard releases and buggy software.

Agile methodologies, seek to accelerate releases of much smaller pieces of code. These releases can happen daily or even many times a day, as developers themselves are given the levers to push code.  Agile tends to be more reactive to business needs, with less planning and requirements gathering up front.

While Agile remains the buzzword of the day, it may not work for every software development project.  Web development & applications where small failures can easily be tolerated and where small teams are at work on the effort, make most sense.

Sean Hull asks on Quora – What is Agile software development and why is it important?

iHeavy Insights 79 – Plumbing the Interwebs

I meet new people all the time.  It’s a way of life in New York.  One of the first questions new people ask each other is “What do you do?”.  It begins to sound like a cliche after a while, but it can also provide endless fascinating discussions as there are so many people with different professions in New York.  Some choose a titled answer “i’m an investment banker”, “I’m an emcee”, “I’m an executive recruiter”.  I find for “Web Scalability Consultant” or “Web Operations Expert” this only leaves confused looks.

A Plumber By Another Name

The solution of course is to tell a good story.  Stories illustrate what titles and crusty vernacular cannot.  I’ve used analogies to surgeons or mechanics, of course they all operate on something people can related to in front of them.  People or vehicles we use everyday.  Of course with the internet, there is a huge hidden infrastructure that most people don’t see everyday.  They may vaguely know it’s there, but it’s still hidden out of site.

That’s why I think plumbing provides such an apt visual.  As it turns out the internet is built with countless data pipes both large and small, coming into your home or laying across the bottom of the transatlantic ocean.  These pipes plug into routers, high speed traffic lights and traffic cops.  Ultimately they feed into datacenters, huge rooms filled with racks of computers, holding your websites crown jewels.  Therein contains the images and status updates from your facebook profile, your banking transactions from your personal bank account or credit card, your netflix movie stream, or the email you sent via gmail.  Even your instant messaging stream, or the data from your favorite iphone app are all stored and retrieved from here.

Amazon Outage

The recent Amazon outage has been high profile enough that a lot of folks who don’t follow the latest trends in web operations, devops, and datacenter automation still heard about this event.  Turns out it’s had a silver lining for Amazon cause now everyone is scrutinizing how many sites actually rely on this goliath of a hosting provider.

As it turns out the root of the amazon outage was indeed a plumbing problem.  Amazon has shown rather high transparency publishing intimate details of the problem and it’s resolution.  Read more.

A misconfigured network cascaded through the system creating countless failures.  If you imagine water repairs being done in a large New York City building, they often ask tenants to turn off their water, so they won’t all come on at the same time when service is restored.  SImilarly intricate problems complicated the Amazon effort, slowing down attempts to restore everything after the incident.  I wrote at length about the outage if you’re interested, read more.

BOOK REVIEW:  Game-Based Marketing by Zicherman & Linder

There are so many new books coming out all the time, it’s tough to sift and find the good ones.  Anyone with a website as their storefront, whether they are a product company or a services company, can gain from reading this book.

From leaderboards to frequent flyer programs, badges and more this book is full of real-world examples where game-based principles are put into action.  On the internet where attention is a rarer and rarer commodity, these concepts will surely make a big difference to your business.

Amazon book link – Game Based Marketing