OceanStore & GPFS

Readings

John Kubiatowicz et al., "OceanStore: An Architecture for Global-Scale Persistent Storage" (2000)

Sean Rhea et al., "Pond: the OceanStore Prototype" (2003)

Frank Schmuck and Roger Haskin, "GPFS: A Shared-Disk File System for Large Computing Clusters" (2002)

Edward Walker, "A Distributed File System for a Wide-Area High Performance Computing Infrastructure" (2006)

Questions

Is it worth it??

Ocean Store

Pros

• Only trust required is own box
• Data is highly durable due to file versioning
• Information divorced from location
  • So long as you can reliably obtain information, it doesn't matter where it is located
• Applicable to many data storage situations, not for a specific case
• Routing is decentralized
• 2/3 of network is up? All is available

Cons

• Very expensive to computer cryptography (slow generation of keys)
• Utility models don't make economic sense, people prefer not to pay for access to their data

GPFS

Distributed local OS designed for clusters Max size of 4096TB

Pros

• Massively parallel - data is striped across many many disks
• Therefor read/write is very fast
• Option of redundancy
• Locking mechanism
  • Two options
    • Data shipping
      • Distributed
      • First client to request access to file receives token
      • Other clients must request the current owner of the token
        • The current owner of the file grants portional access to their file (breaks token and gives portion access)
    • Centralized locking
      • Faster in a small disk circumstance
• Extreme reliability
  • Able to literally remove a hotswap disk and insert a blank one in its place, only to have the blank disk completely regenerate the missing data
  • Journalling to record token ownership - helps recovery when node in possession dies

Cons

• Everything must be trusted! Designed for clusters, not across LAN/WAN
• Not appropriate for distributed networks.

XUFS

• User-space implementation
• Designed to be simple
• Very generic