DistOS 2014W Lecture 14

OceanStore

What is the dream?

• High availabitility, universally available.
• Utility managed by multiple parties
• Highly redundant, fault tolerant
• Basic assumption was that servers would NOT be trusted.

• Highly persistent
  • Effective archival
  • Everything saved, nothing deleted. "Commits"

• Service was untrusted
  • Held opaque data.
• Would be used for more than files. DB's, etc.

Why did the dream die?

Technology

• The trust model is the most attractive feature which ultimately killed it.
  • The untrusted assumption was a huge burden on the system. Forced technical

  limitations Made them uncompetitive.

• • It is just easier to trust a given system
  • Every system is compromisable despite this mistrust
• Pub key system reduces usability
  • If you loose your key, you're S.O.L.
• security
  • there is no security mechanism in servers side.
  • can not now who access the data

Use Cases

• Subset of the features already exist
  • Black berry. Google.
  • Current services owned by one company, not many providers.
  • Can not sell back your services as a user.
    • ex. Can not sell your extra storage back to the utility.

Pond: What insights?

• They actually built it.

• Can't assume the use of any infrastructure, so they rebuild everything!
  • Built over the internet.
  • Tapestry
  • GUID for object indentification. Object naming scheme.

Benchmarks

• Really good read speed, really bad write speed.

Storage overhead

• How much are they increasing the storage needed to implement their storage model.
• Factor of 4.8x the space needed (you'll have 1/5th the storage)
• Expensive, but good value (data is backed up, replicated, etc..)

Update performance

• No data is mutated. It is diffed and archived.
• Creating a new version of an object and distributing that object.

Other stuff

• Byzantine fault tolerance
  • Assuming certain actors are malicious