Sourkraut! Or freeze it but crocks take only a little room. There's recipes for canned cabbage, usually called quick kraut but that's just pickling it.
Have you tried making saurkraut like these folks. Very good but salty.
Have you tried fermentation? It's all about percentage of salt and temperature. The salt part is easy, use canning salt and weigh everything. Shoot for 4 percent.
They go great diced in stews and casseroles too - especially Irish stew they compliment the flavor of the Lamb really well.
Sauerkraut is easy to make, but once in awhile it seems to go off the rails. Don't use too much salt. It shouldn't need a lot. There are a lot of good recipes on line so you can read up and figure out what really works best. I like to stick to basics (and no caraway seeds). Just shredded hard cabbage and salt. 3 to 6 Tablespoons per 5 lbs of cabbage is all you need depending on how salty you like it. And it must be non-iodized salt. So no table salt! Either Sea, kosher or canning salt. It should keep just fine without canning for up to a year due to the lactic acid from the natural fermentation. If you do choose to can it, be very careful not to overdo it - just enough to sterilize the air n the top of the jar and don't cook the cabbage. Otherwise, it goes soft and mushy very quickly.
I used 3 tablespoons per 5 lbs of cabbage. It is pretty salty tasting at that strength. I put mine into sterilized quart jars and loosely put the lid on them and stuck them in the fridge. About 2.5 months later they were moldy and threw them out so that doesn't work long term.
