5. The views reflected in this talk
are not to be considered a
reflection of the skills of my
coworkers who are extremely
nice human beings and way
better at capacity planning
than I am.
😜
NOTAmonitoring
person
💀
🚨🚨
12. I Rule the
Edge!
Evaluates weekly global
POPs performance &
makes projections
Publishes capacity
performance report in
clear location
Plans for our physical
capacity & transit
capacity
Meet Catharine
13. Planning Our Capacity
Some metrics
- Network Capacity (Gb)
- Ordered Network Capability (Gb)
- Planned Network Capacity (Gb)
- RPS Capacity (k)
- Network peak (Gb)
- RPS peak (k)
- Site CPU Peak (%)
- Network Utilization (%)
Over 30%: flagged, Over 70%:
Red status
14. Edge Insights
Our ability to correctly plan for
capacity is critical to our
bottom line
Capacity doesn’t just involve
hardware; software
optimizations matter
People affect capacity
16. Defining Capacity planning
Measuring, planning, & managing system growth
Determines what your system needs & when
From the observation of actual traffic. Use current
performance as baseline.
Must happen regardless of what you might
optimize
17. ARE
WE RIGHT
NOW?
We have to be
this fast & reliable
X per second & Y%
Uptime
MEASURE HOW/RELIABLE WE ARE
HARDWARE
SOFTWARE
ARCHITECTURE
CHANGE / ADD / REMOVE
FIGURE OUT
HOW TO STAY
FAST/RELIABLE
ENOUGH
Yes!
No!
Allspaw's Wisdom
From The Art of Capacity Planning
👈
18. System’s Ceiling: critical level of a
resource that cannot be crossed
without failure. Find yours
Another form of Capacity Planning:
Controlled load testing
Predictions: ceilings + historical data
Allspaw's Wisdom
19. Allspaw's Wisdom
System architecture can affect your
ability to add capacity
Identify & track your application’s
metrics
Tying metrics to user behavior is helpful
If you don’t have ways to measure
your current capacity you can’t plan
20. Little’s Law & Capacity planning
L = λW
Capacity (L), Throughput (λ),
and Latency (W)
Applies to stable systems
Use this information to better
understand our workload and to
define constraints
21. Literature Insights
Possible to have plenty of capacity and
a slow site nonetheless
Projections & curve fitting are guesses
Keep track of API calls & their rate
Always gonna be spikes & hiccups.
Take the bad with the good & plan for it
25. Industry Insights
Hard to extrapolate general
advice into something
applicable for my situation
Simplicity & ability to reason are
the only things I could trust
Confusing community stance on
the ROI of capacity planning
27. Step One Step Two
steps followed
Documented system
architecture &
request lifecycle
Formalized: clients,
SLAs, & operational
requirements
Discovery
Confirmed constraints
& determined strategy
Parallelized capacity
& optimizations tasks
Organized a team
Gauging & Planning
28. Edge
Core APP / API APP / API
LB LB
COORDINATOR A COORDINATOR B COORDINATOR C
🐤
CACHE
LON
CACHE
DFW
CACHE
FRA
CACHE
LAX
CACHE
AMS
CACHE
SYD
REQUEST flow
📄 📄 📄👉
29. Step Four
steps followed
Start process again
Tons of tuning left to
do. We know we
have suboptimal
configs!
re-Evaluation
Step Three
Doubled RAM: our
constrained resource
Horizontally scaled to 3
servers + 1 canary
Capacity expansion
34. Unexpected Challenges
Our goal when adding capacity
was no service disruption.
Localhost is the goddamn devil
Gap from metric/graph to
insight can be huge
Slowness is the nemesis of
distributed system
35. The Oprah Problem
Developing operational
insights into non-owned
system under pressure is
not great
Use playbooks,
debug.md, rotations, &
rollout owners
Proactivity and clarity
are your best tools
Everyone
gets more
capacity!
36. Some Insights
Anything API driven ought to
carry a rate limit - We can
easily DDOS ourselves!
Monitor and alert on
expensive API actions
Mind your system
dependencies: practice
defensive system design &
architecture
CAPACITY
PLANNING
ALERTING
MONITORING
37. Some Findings
Capacity tied to murky
organizational structure
is both good & bad
(but mostly bad)
Mind your error
descriptions! Cheeky
today ⇒ misleading
tomorrow!
38. Finding my system’s ceiling is still tricky
Services owned by engineers means
you need to level up on Ops skills
Back to re-evaluate setup to get more
out of this new capacity
Performance testing ought to be done
on the core’s side (& edge)
My Insights
39. TL;DR
Is a process not a one
time event
Pushes you to better
understand your
system, its capacity &
its boundaries - that is
good!
Proactivity is best
Capacity planning
Request lifecycle gets
tricky
System boundaries,
dependencies & SLAs
must be discussed
Your system’s capacity
may bound other
systems capacity
Distributed systems