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Re: Determining the usefulness of compression


Am 20:44 2002-12-04 -0800 hat Vineet Kumar geschrieben:
>> filename suffixes (never bother with gz, tgz, bz2, zip, jpg, jpeg, gif, z,
>> Z, mpg, mpeg, avi, wav, mov....)
>Huh? some AVIs and all WAVs are uncompressed, and will benefit
>enormously from compression.  The theory here is correct, though:

Be careful with 'wav', becaus you can use pcmdvi compression,
which reduce the size about 70% (and if you play it, it will
decompressed On-The-Fly)

>> compress a sample of the file (first and last 4k blocks maybe?)
>> test for magic numbers that indicate compressed types
>> Don't bother for files less than 1k

I think, it depends on the filesystem...
If you have made a filesystem with blocks  of 4 kByte, it is better,
you compress only files bigger then 4096 Bytes...

I use 16kByte blocks on my /home and 8kByte for the maildir.

If your MUA supports (de)compression on the fly for maildir,
you can beefit, if you use 1 kByte blocks and use bz2.

This month has already 4556 messages and only 217 files are bigger
then 1 kByte bz2 compressed...

>Or tar them up and compress the whole thing.  If you have a lot of
>little text files, or a lot of little wavs, you'll save a lot of space
>with a compressed tarball.

If you setup a new Computer, maybe it is better you plan correctly
the partitions and the filesystem...


P.S.:   The user-maildirs in /home are symlinks  to the Partition
        with the 1 kBlocks.

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