Why was the newst copy of enwiki with the full history removed from the downloads site? I checked around and was only able to find one place with it: http://www.archive.org/details/enwiki-20080103
You'll want the "enwiki-20080103-pages-meta-history.xml.7z" file, which is about 17GB. There is another file that is 130GB, but that is the SAME thing, just compressed with bz2 insteaf of 7z, making it larger, so don't get that one.
Tomasz, I am willing to volunteer my services as a programmer to help with this problem in making full history enwiki dumps, if it is possible (I can't donate hardware/money). What are the issues which are causing it to be so slow and what methods are you employing to improve it?
I know that LiveJournal has some sort of live backup system using MySQL and Perl, but couldn't find any details on their presentations. You might be able to ask one of their developers for help, on their LJ blog. Can Wikimedia afford a snapshot server? It doesn't need to be as fast as the others.
In the long run, whatever this system is, it will probably need to be integrated into some sort of backup, because it would be a huge pain if something happened at the data center and you needed to restore from the partial quasi-backups in the current systems.
How does the current dump method work? Are they incremental in the sense that they build up on previous dumps, instead of re-dumping all of the data?
For future dumps, we might have to resort to some form of snapshot server that is fed all updates either from memcaches or mysqls. This allows for a live backup to be performed, so it's useful for not just dumps.
Is it possible to suspend any individual slaves temporarily during off peak hours to flush the database to disk and then copy the database files to another computer? If not, we may still be able to use a "stale" database files copied to another computer, as long as we only use data from it that is at least a few days old, so we know that it's been flushed to disk (not sure how mysql flushes the data...).
Of course, this may all be totally off, since I don't know a lot about the current configuration and issues, so I'll take whatever input you have to help work on something better.