The magic of ReiserFS
Michael
michael at photorequest.co.uk
Mon Nov 23 19:51:22 CET 2009
I bought an 8GB micro sd card with the intention of storing
OpenStreetMap tile for Tango GPS onto it. I could store up to zoom
level 14, but zoom level 15 was one step too far in terms of size. I
knew this was due to the block size of the filesystem, but even a
block size of 512 bytes would have a lot of overhead. I had read about
the small file performance of reiserfs, so I thought I would give it a
try. I created a sparse file reiserfs filesystem and loopback mounted
it and copied the files up to zoom level 15 onto it. Amazingly the
sparse file only grew to 2.6GB while the tar file for zoom level 14
alone was 2.5GB. I copied the sparse file onto the micro sd, inserted
it into the Neo, and booted it with a reiserfs enabled kernel. The
file mounted on the Neo ok and Tango GPS seemed to be able to read the
files ok (made sure it could do it with the internet disconnected).
I ran a du on the Maps directory and it came to 9.7GB, but reiserfs
managed to get the storage down to 2.6GB which certainly seems like
magic, especially since it also managed to outdo tar as well. I am
going to see if I can get zoom level 16 onto the card as well.
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