MOAT: A MultiObject Assignment Toolkit

1
MOAT A Multi-Object Assignment Toolkit

• Haifeng Yu
• Intel Research Pittsburgh / CMU
• Joint work with
• Phillip B. Gibbons
• Intel Research Pittsburgh

2
Multi-object Accesses

• Many user accesses request multiple data objects
  / files
• Compile a project / Writing a paper under Latex
• Query for aggregates of network conditions
• Availability of single object can be misleading
• An access requesting 1,000 objects can observe up
  to 1,000 times higher unavailability
• Theres more subtlety.....

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Replica Assignment Example
C
D
C
D
C
D
C
D
C
D
4 files
A
B
A
B
A
B
A
B
A
B
4 machines
which is better?
2.4
access requesting 500 files

• Compile a project
• need all 4 files

0.3
nines of availability
4.5

• Computing an aggregate
• may tolerate one missing object

query requesting 500 objs but tolerate 7 missing
objs
2.4
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Goal and Contributions

• MOAT (Multi-Object Assignment Toolkit)
• Goal High availability for multi-object accesses
• Key issue Replica assignment
• Contributions (applicable to both replication and
  erasure coding)
• First to observe the importance of replica
  assignment
• Strong theoretical results regarding best and
  worst assignments
• Practical designs to approximate optimal
  assignments
• MOAT toolkit implementation for replica
  assignments