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

Pond

Example of oceanstore

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

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Distributed

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First client to request access to file receives token

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Other clients must request the current owner of the token

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The current owner of the file grants portional access to their file (breaks token and gives portion access)

---Centralized locking

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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