Embedded Linux: Using Compressed File Systems
Posted Feb 8, 2007 13:26 UTC (Thu) by endecotp
Parent article: Embedded Linux: Using Compressed File Systems
I know of only two filesystems that are both writeable and compressed: jffs2 and e2compr. jffs2 works only on directly-connected flash (i.e. not the USB and IDE flash drives that I use), and IIRC e2compr is not included in the kernel because it doesn't have any fsck support, which is rather worrying to say the least. The remaining option is to use a union filesystem to combine a read-only compressed filesystem with a writeable uncompressed filesystem. This is fine at first but becomes useless once you've "apt-get upgrade"ed - eventually it uses more space than a normal uncompressed filesystem would have done.
So there's definitely scope for improvements. There are other things you could do, such as initially storing the data uncompressed and having a low-priority background process do the compressing once files seemed to be stable. Maybe this could happen as part of the journal writeback system?
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