Design of Parallel Systems


Design of Parallel Systems
Some issues in the design of parallel systems:
􀂄 Parallel loading of data from external sources is needed in order
to handle large volumes of incoming data.
􀂄 Resilience to failure of some processors or disks.
􀃌 Probability of some disk or processor failing is higher in a parallel
system.
􀃌 Operation (perhaps with degraded performance) should be possible
in spite of failure.
􀃌 Redundancy achieved by storing extra copy of every data item at
another processor.

􀂄 On-line reorganization of data and schema changes must be
supported.
􀃌 For example, index construction on terabyte databases can take
hours or days even on a parallel system.
􀂾 Need to allow other processing (insertions/deletions/updates) to
be performed on relation even as index is being constructed.
􀃌 Basic idea: index construction tracks changes and ``catches up'‘ on
changes at the end.
􀂄 Also need support for on-line repartitioning and schema changes
(executed concurrently with other processing).

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