Lessons Learned While Building Infrastructure Software at Google

Table of Contents

1 GFS

  • Developed by subset of same people working on indexing system
  • Identified minimal set of features needed

    • e.g. Not POSIX compliant
    • actual data was distributed, but kept metadata centralized
    • Colossus: Follow-on system developed many years later distributed the metadata
  • Lesson: Don’t solve everything all at once

2 MapReduce

  • Developed by two people that were also doing the indexing system rewrite
    • squinted at various phases with an eye towards coming up with common abstraction
  • Initial version developed quickly
    • proved initial API utility with very simple implementation
    • rewrote much of implementation 6 months later to add lots of the performance wrinkles/tricks that appeared in original paper
  • Lesson: Very close ties with initial users of system make things happen faster
    • in this case, we were both building MapReduce and using it simultaneously

3 BigTable

  • no distributed transactions, no cross-row joins
  • initial design was just in a single cluster
  • follow-on work added eventual consistency across many geographically distributed BigTable instances

4 Spanner

  • Several variations of eventual client API
  • Started to develop with many possible customers in mind, but no particular customer we were working closely with
  • Eventually we worked closely with Google ads system as initial customer
  • Different API than BigTable
    • Harder to move users with existing heavy BigTable usage

5 Designing & Building Infrastructure

  • Identify common problems, and build software systems to address them in a general way
  • Important to not try to be all things to all people
    • Clients might be demanding 8 different things
    • Doing 6 of them is easy
    • handling 7 of them requires real thought
    • dealing with all 8 usually results in a worse system
    • more complex, compromises other clients in trying to satisfy everyone
  • Don't build infrastructure just for its own sake:
    • Identify common needs and address them
    • Don't imagine unlikely potential needs that aren't really there
  • Best approach: use your own infrastructure (especially at first!)
    • (much more rapid feedback about what works, what doesn't)
  • If not possible, at least work very closely with initial client team
    • ideally sit within 50 feet of each other
    • keep other potential clients needs in mind, but get system
    • working via close collaboration with first client first

6 Data Center

cordboards

google-corkboards.png

data centers

google-data-centers.png

machines

google-machines-inter-connection.png

google-machines-rack.png

cool system

google-cool-system.png

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