Re: one idea about reiser4 compress

[David Masover <ninja@slaphack.com>]

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Linuxhippy wrote:
> Hi Jun!
> 
>> Assume you install a distribution on a compressed partition with reiser4.
>> you usually do like this --
>>
>> | CD | Installer with decompression | -> | Re-compress with Reiser4 |
>> HDD |
>>
>> You dont think decompression -> recompression cycle is wasteful?
>> If CD contains compressed files with reiser4 compression format,
>> I guess it is possible to do like this --
>>
>> | CD with reiser4 compressed files | Installer | -> | HDD |
>> I mean, this eliminates an overhead of re-compression and make whole
>> isntall process simpler and faster. Maybe you could do install like
>> this --
>> # cp -a /mnt/cdrom /mnt/target_hdd
>> And this way would be much faster than usual installer today.
>>
>> How about this idea?
>>  
>>
> 
> To be honest I do not think your idea can be realized in a useful way
> because of:
> a.) Every Installer uses its own compression format, most time those
> packages have additional fines in it like install scripts and so on.

So support zisofs, if we're talking about a CD.

> b.) Reiser4.1 compression will eb definitivly optimized for speed,
> installer-packages are usually heavily optimized for size.

Right.  Hopefully, we'd have different algorithms supported, and zisofs
compression is gzip, which might be useful.  If it's not, then this
becomes a transcoding problem (convert gzip-to-zlib with no
decompression/recompression) which is beyond the scope of Reiser.

> c.) You would need new API's to archive this. Either through syscalls or
> via reiser's special files.

Special files are supposed to be easier than that.  Assuming that we
have a decent standard to allow custom extensions, the API should be no
big deal.  Look at XML's namespaces for a good exaple of such a standard.

> Conclusion: It would be a major hassle to implement such stuff for next
> to null advantages. There are so many (important) features waiting to be
> implemented ;-)

I agree there, but I won't be the one implementing it, and chances are
you won't either.
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