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Architecture - HSM and Cache

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Multiple Lustre features have significant overlap because they involve migration of file system objects:

  • HSM
  • Space rebalancing
  • Data migration
  • Caches for Lustre proxy services
  • Server Network Striping rebuild
  • 3rd party IO


The architecture under consideration will target re-use of components.

Software Subsystem Decomposition


Migration enables an initiator to request that file data is read from one location and stored in another.

  1. 3rd Party IO - A node requests through a lustre client that data can be read/written through a 3rd party transport
    1. the node gives {R,W}, offset, length, and a transport id, and transport data to a Lustre client
    2. the Lustre client decodes the ranges of the file that reside on OSS nodes and forwards corresponding range descriptors in the file and in the objects to the OSS nodes
    3. the OSS nodes prepare pages for the IO corresponding to the object ranges that need to read/written.
    4. the OSS calls a 3pio_init(transport id, object range_desc, file_range_desc, transport_data, &3pio_fini, cb_data). There are rules
    5. the 3rd party transport