Yaouh! out (update for tangogps maps)
billk at iinet.net.au
Tue Jan 20 11:44:19 CET 2009
On Tue, 2009-01-20 at 11:00 +0100, Helge Hafting wrote:
> William Kenworthy wrote:
> > ...
> > Where I live (Perth, Western Australia) there are large areas of
> > surrounding sea/land/forestry/desert etc that use a single colour tile -
> > each of only 103 bytes. I symlinked all identical files (based on
> > md5sum) such that only one copy of each is kept. This has the advantage
> > that as ext2/3 uses fast-symlinks, the actual symlink (provided the path
> > is < 60 characters) is stored in the inode and doesnt take any block
> > space on the FS. This shrinks the size as given by du -sh from 3.3Gb
> > down to ~550Mb.
> Interesting idea. Half of my tiles are blank too.
> But what happens when tangogps (or yaouh or whatever)
> re-downloads some previously blank tile that now has a new road on it?
> Will the link break for that tile? Or will the sole blank tile be
> replaced, so that every blank area now has the same road on it?
> I don't keep a tile repositiory on my desktop, I download
> directly to the freerunner.
> Helge Hafting
Check if you have run out of inodes - there are only so many to go
around! - this was a problem foe until I realised it as it looks like
there is plenty of room, but strange crashes and the like occur as there
are no free inodes.
$ echo aa > aa
$ ln -s aa bb
$ echo cc > bb
$ cat aa
So it will overwrite. Not a problem for me as I dont use gprs (too
expensive in Oz for casual use, and coverage is miserable outside the
central capitals and large towns.) and the desktop system is always the
master. Started out this way as kept losing the partition in the early
days and ext2/3 is not a very good filesystem for devices like this
anyway, corruption occurs quite readily so I dont trust it :)
Alternatively, identify the symlined master and make it read only - wont
update, but wont overwrite all similar tiles either.
Also, I didnt think tangogps overwrote files already downloaded - it
uses them from the cache instead - will have to test the download
dialog, but I seem to remember that didnt download existing tiles
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