[OSM-dev] tiles at home disk usage
Jeroen Dekkers
jeroen at vrijschrift.org
Wed May 2 14:09:48 BST 2007
At Wed, 2 May 2007 12:02:51 +0200,
Frederik Ramm wrote:
>
> Oliver,
>
> > Just as background info for anyone who doesn't watch munin stats:
> > the sea and
> > coastline tiles have pushed us up to 92% disk space usage (from 57%
> > before)
> > on tiles at home
>
> Two questions on that.
>
> 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.
Do you count the right column? I count 66GB. Here is a nice table:
layer 1 layer 2 layer 3 total
zoom 0 22,480 0 12,797 35,277
zoom 1 55,612 0 31,231 86,843
zoom 2 134,877 0 74,678 209,555
zoom 3 325,737 0 189,342 515,079
zoom 4 776,655 0 498,861 1,275,516
zoom 5 1,876,724 0 1,334,747 3,211,471
zoom 6 6,925,280 0 3,118,934 10,044,214
zoom 7 10,719,525 0 7,717,831 18,437,356
zoom 8 25,339,412 0 18,309,130 43,648,542
zoom 9 60,292,249 0 40,802,845 101,095,094
zoom 10 166,032,741 0 108,227,213 274,259,954
zoom 11 456,792,268 0 258,925,376 715,717,644
zoom 12 229,182,865 661,252 327,060,425 556,904,542
zoom 13 574,283,357 1,349,422 859,039,865 1,434,672,644
zoom 14 1,289,658,006 3,302,032 2,028,254,098 3,321,214,136
zoom 15 2,968,696,667 7,267,224 5,019,642,154 7,995,606,045
zoom 16 7,405,587,097 16,464,946 10,904,265,715 18,326,317,758
zoom 17 20,557,170,910 37,190,295 13,057,235,718 33,651,596,923
total 33,753,872,462 66,235,171 32,634,740,960 66,454,848,593
And here is a table for the number of tiles:
layer 1 layer 2 layer 3 total
zoom 0 1 0 1 2
zoom 1 4 0 4 8
zoom 2 16 0 16 32
zoom 3 64 0 64 128
zoom 4 256 0 256 512
zoom 5 1,024 0 1,024 2,048
zoom 6 4,096 0 156 4,252
zoom 7 1,348 0 624 1,972
zoom 8 5,270 0 2,496 7,766
zoom 9 21,077 0 9,984 31,061
zoom 10 84,312 0 39,936 124,248
zoom 11 337,223 0 159,744 496,967
zoom 12 59,434 39 63,081 122,554
zoom 13 159,725 122 151,029 310,876
zoom 14 453,553 388 358,092 812,033
zoom 15 1,339,015 1,144 854,981 2,195,140
zoom 16 4,195,982 3,155 2,055,509 6,254,646
zoom 17 14,131,388 7,802 3,232,215 17,371,405
total 20,793,788 12,650 6,929,212 27,735,650
> The empty sea tiles are, as far as I can think of, the only thing
> that was really added by the new software. The coastal tiles were
> there before, with a thin blue line for the coastline instead of a
> blue area, which should not make a world of a difference in terms of
> PNG file size.
A tile which is fully the same colour is 571 bytes. That can also be
green tiles from parks etc, but I guess most of them is water. I count
12,698,593 of them. That would be 6.5G in size. But if they have to be
stored in 512 bytes sectors, that would mean 1024 bytes of diskspace
used per tile, making it 13G in total.
I've attached the script to generate the numbers. It's quickly hacked
up and could use some refactoring however...
Jeroen Dekkers
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