Im making my own offline wiki (fun side project). EN wiki dump is ~10GB. 8-9GB if you preprocess XML dropping useless tags and wikimarkup

  falink = {b'Link FA|', b'Link GA|', b'link FA|', b'link GA|', b'Link FL|', b'link FL|'}

different language links/references, every article has a list of all the language version links (ex: [[af:April]] [[als:April]] ..)

  langcolon = {b'aa:', b'ab:', b'ace:', b'af:', b'ak:', b'aln:', b'als:', b'am:', ................-my:', b'zh-sg:', b'zh-tw:', b'zh-yue:', b'zu:'}

I have a feeling changing wikimarkup to something more size optimized would help even more. Swapping compression algorithm can squeeze additional 1-3GB of savings without sacrificing decompression speed.

All in all with a lot of tricks you can go from 10GB to 5GB. Doesnt feel worth it. Bigger problem is searching thru this data on a 2-4 core ~1GHz ARM processor with 1-2GB of available ram. Indexing titles is simple and fast, but quite useless. Indexing all useful words would eat at least couple of gigabytes. Searching for a simple combination of three words would take couple of seconds every time. Its not like you can haul Hadopi cluster in your pocket.