[OSM-dev] tiles at home disk usage

Martijn van Oosterhout kleptog at gmail.com
Wed May 2 11:33:25 BST 2007


On 5/2/07, Frederik Ramm <frederik at remote.org> wrote:
> First, if I sum up all sizes given in the latest.txt.gz file, I end
> up with the number 502032007251339, that's roughly 500 GB. Do we
> really have that amount of tile data, or is there something wrong
> with either the file or my sum? From my calculations, the empty sea
> tiles seem to make up only about 6 GB, but if 500 GB tile data is 92%
> disk usage and you only had 57% before, then that means that not 6 GB
> but 200 GB have been added recently.

One thing I wonder about is the so called "tail compaction" and
filesystem overhead. Empty tiles may be small, but if they're not
compacted then they'll take kilobytes per file. If you take the number
of empty tiles and multiply by the block size, does that come closer
to the estimate? Secondly, if files are often created and deleted,
perhaps some of the internal filesystem structures are bloating?

Is there any way to measure the actual system overhead?

Have a nice day,
-- 
Martijn van Oosterhout <kleptog at gmail.com> http://svana.org/kleptog/




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