The magic of ReiserFS
David Garabana Barro
david at garabana.com
Mon Nov 23 22:13:23 CET 2009
O Luns, 23 de Novembro de 2009, Michael escribiu:
> 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.
Yes, I have tried to put several tangogps tiles on ext3 (before OM kernel
supported ReiserFS), but even with minimal blocksize, overhead was too much.
You had also to raise inodes to several millions when creating the fs, and I
ran out of inodes several times...
With ReiserFS, wasted space is minimal, thanks to tailpacking, and you forget
about inode limits. :)
David Garabana Barro
jabber & google talk ID: david at garabana.com
Clave pública PGP/GPG: http://davide.garabana.com/pgp.html
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