Re: Transparent compression in the FS

[Eli Carter <eli.carter@inet.com>]

John Bradford wrote:
>>What might be worth considering is internal NUL detection.
>>Build the block-of-zeros detection into the filesystem
>>write resulting in automatic creation of sparse files.
>>This could even work with extent based filesystems where
>>using hashes to identify shared blocks would not.
> 
> 
> Another idea could be writing uncompressed data to the disk, and
> background-compressing it with something like bzip2, but keeping the
> uncompressed data on disk as well, only over-writing it when disk
> space is low, and then overwriting the least recently used files
> first.
> 
> The upshot of all that would be that if you needed space, it would be
> there, (just overwrite the uncompressed versions of files), but until
> you do, you can access the uncompressed data quickly.
> 
> You could even take it one step further, and compress files with gzip
> by default, and re-compress them with bzip2 after long periods of
> inactivity.

Note that a file compressed with bzip2 is not necessarily smaller than 
the same file compressed with gzip.  (It can be quite a bit larger in fact.)

Eli
--------------------. "If it ain't broke now,
Eli Carter           \                  it will be soon." -- crypto-gram
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