Lock Services in Distributed File Systems - PowerPoint PPT Presentation

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Lock Services in Distributed File Systems

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No fault recovery. Analysis - Chubby. Low volume storage. Flat access ... File handles and advisory locks. Event notification service. KeepAlive piggybacking ... – PowerPoint PPT presentation

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Title: Lock Services in Distributed File Systems


1
Lock Services in Distributed File Systems
  • Shaan Mahbubani
  • Anshuman Gupta
  • Ravi Vijay
  • Anup Tapadia

UCSD CSE 221 Operating Systems - Winter 07
2
Distributed File System Lock Service
  • Synchronization
  • Consistency
  • Access control
  • Shared access

3
Farsite - Overview
  • Goals
  • Meta-data partitioning
  • Namespace consistency
  • Scalable
  • Design
  • Recursive path leases
  • File-field leases
  • Disjunctive leases

4
Chubby - Overview
  • Goals
  • Coarse-grained synchronization
  • Primary election
  • Design
  • High capacity
  • Server, client library
  • Sessions, events, client caching

5
Analysis - Farsite
  • Fully functional rename
  • Identifier based partitioning
  • Fine grained synchronization leases
  • Logical atomicity
  • Optimizations
  • Recursive leases
  • Lazy updates
  • No fault recovery

6
Analysis - Chubby
  • Low volume storage
  • Flat access control lists
  • Lock service in lieu of consensus service
  • File handles and advisory locks
  • Event notification service
  • KeepAlive piggybacking
  • Client side caching

7
Comparison
Farsite Chubby
Meta-data distribution Dynamic Centralized
Partitioning File ID None
Rename Fully functional Not across dir
Update policy Operation replay Update as deltas
8
More Comparison
Farsite Chubby
Locking Mandatory Advisory
Load Balancing Delegation None
Fault Recovery None Reconstruction
Bandwidth utilization Low High
9
Even More Comparison
Chubby Farsite NFS AFS
Meta-Data partitioning ? File ID Pathname File ID
Full rename ? Yes ? ?
Access Control Flat Hierarchical Hierarchical Hierarchical
10
Questions
  • Farsite
  • Scalability
  • Lease overhead penalty
  • Network robustness
  • Effect of malicious machines
  • Time to recovery
  • Chubby
  • API problems
  • Throughput bottlenecks due to keepalives
  • System capacity

11
Conclusion
  • Farsite locking
  • Distributed directory service avoids hotspots
  • Fine grained locking avoids false sharing
  • No fault tolerance
  • Chubby locking
  • Lock service is better than consensus service
  • Coarse grain locking more useful
  • More reliable across failovers

12
Thank You !
  • Questions ?
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