Changes between Version 2 and Version 3 of Ticket #510, comment 22


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Timestamp:
2013-05-30T00:18:43Z (11 years ago)
Author:
daira
Comment:

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  • Ticket #510, comment 22

    v2 v3  
    22
    33Currently, the cloud backend splits shares into "chunks" to limit the amount of data that needs to be held in memory or in a store object (see [source:docs/specifications/backends/raic.rst]). This is somewhat redundant with segmentation: ciphertext "segments" are erasure-encoded into "blocks" (a segment is k = {{{shares.needed}}} times larger than a block), and stored in a share together with a header and metadata, which is then chunked. Blocks and chunks are not aligned (for two reasons: the share header, and the typical block size of 128 KiB / 3, which is not a factor of the 512 KiB default chunk size). So,
    4  * a sequential scan over blocks will reference the same chunk for several (typically about 12) consecutive requests.
     4 * a sequential scan over blocks will reference the same chunk for several (typically about 12 for k = 3) consecutive requests.
    55 * a single block may span chunks.
    66