Scale Summit is an unconference which talks about web, scalability, performance, operations and lots of fun things. Michael described it as like full day of Velocity hallway track, which is a pretty accurate description, and also an inspiring objective to aim for.

It is run as a open space unconference using Chatham House rules, which enourages frank, open discussion where people can bring their real-world problems to their peers and get ideas for how to solve them.

This is my notes of the event. There are many like it, but this one is mine.

Setting up ELK

This was a session about using ELK and what good looks like:

  • people are broadly happy with AWS options for IO / CPU / RAM
  • there are good elasticsearch plugins for snapshotting, cluster management
  • upgrading a cluster used to be a pain, but is becoming less so
  • no reported JVM issues with losing data (which used to be an issue with Lucene and some JVMs)
  • Splunk is very expensive compared with elastic at the volumes people were discussing
  • run logstash as an agent on each node, rather than tailing logs, for better performance. Similar to a statsd model

Scaling Graphite

This was a session about hitting limits with Graphite and what to do next:

  • is graphite still the right answer? Probably, it still has a way to go and you can swap out parts of a graphite solution for more performant options which are reasonably drop-in
  • Fusion IO gives great performance for this part of a system (make sure they’re cooled sufficiently though!)
  • InfluxDB and other options?
  • community is unsure about graphite roadmap, now that a core committer essentially works at a competitor
  • viewing graphite as a protocol, rather than an implementation. Is the protocol good enough / extensible?

SPDY / HTTP2 inside (and outside) the DMZ

This was a session about the advantages of using HTTPS everywhere and getting good performance.

  • TODO(jabley): update with a link to gdstechnology post afer Purdah when I can publish stuff.
  • talk about timescales for the general web. Agreed that it looks a little way off an upgrade
    • circled back to context where you control the server and client. Good benefits there
  • difficulty in detecting whether the client supports HTTP2
    • No JavaScript solution at the moment
    • Must do server-side detection
    • Existing servers don’t expose this either – write your own?
  • what does this do to caching generally?
  • Speculated about CDN vendors implementing transforming proxy that detects HTTP2 usage, rewrites content to avoid domain sharding and pre-emptively send assets to the client.

Changing the enterprise

This was a session about how to influence people. I slightly switched off here, since I was writing a lightning talk for later.

  • importance of having champions (eg Francis Maude and Martha Lane Fox in the case of GDS)
  • relating on a human level
  • cookie approach - provide food and talk about stuff. People will come for the food, and stay for the learning
  • fixing things for other people
  • lots of recommended reading from this session:

What’s new at Scale Summit

Traditional end of day session reviewing last year’s topics, what’s changed, and what we think will happen over the coming year.

Phil Potter took his usual fabulous notes in 2014, and we have these notes from 2015.

Lightning talks

I was greedy and did a couple of lightning talks (well OK, I was asked to do the Code Club one).

Soft real-time interrupts for squishy humans

TODO(jabley): Update slides with images and put online, then link to them.

This was a talk about using Occupy handsignals / British Sign Language to communicate in meetings. I was first introduced to these at a fort event, and found it very useful and natural way to have better communication over another channel in a respectful way.

Code Club and education in this country

Talk about the progress by Dr Tom Crick to get Computer Science on the curriculum. That’s happening; primary and secondary ITC no longer means knowing how to use office software. But there is a gap / shortage for the skills needed to teach this. We have the skills to get involved and help. Code Club is one such approach. It’s very rewarding to see the kids progress. For some, it’s also a little frightening – the children are in some areas more expert than their teachers.

See also for other exercises that explore problem-solving without having to programme.


The big reinforcement for me is the importance of talking and participating, to get the most out of this event. I had great conversations as a result of both my lightning talks. People were curious how to introduce signs at their workplaces. People were passionate about Code Club, and wanted to share experiences with problems encountered.

Had a great time again, will definitely be going next year.