quick guide on backing up your tumblr from someone who has tried it various ways over the years
so, you noticed that tumblr is so understaffed that they didn't even do april fools this year and you're thinking of backing up your tumblr. maybe even using tumblr's built-in export function.
there are plenty of third party apps that will scrape your blog and grab all the posts. tumblr-utils is one that i have used historically to great effect. another option here. or find your own.
however, if you want to save your dms and asks, you need to use tumblr's export function.
first go to your blog settings and click export blog. you'll get an email when it finishes exporting. this may take a couple days.
now, my blog's file was about 400GB. that's almost half a terabyte. it's a lot of data. there's no way to shrink it or only download parts. it also will not tell you how big the file is going to be. my blog has ~250k posts and another 5k unanswered asks. and yours will probably scale with that.
(this is a good reason to use third party scrapers instead, by the by. tumblr-utils at least allows you to 1) download only your own original posts and not reblogs, 2) download only text and not media, and 3) download in batches not all at once. you're not forced to take the whole thing, which is a lot of data. the html result from tumblr utils is also more usable than the one from tumblr as well).
anyway. the first thing you'll want to do is make sure you choose what folder something downloads to. you do NOT want half a terabyte in your downloads folder. you want it going straight to an external drive. you can set firefox to open a little "save as" dialogue box everytime you download something, which honestly i would recommend doing anyway. or you can use a download manager like jdownloader, which will also help in other ways. though personally i found that jdownloader seemed to choke on the fact that tumblr doesn't tell you the size of the download, and that meant i couldn't interrupt the download or jdownloader would assume it was done.
second is just. make sure your external drive is big enough. i ended up literally bailing out files onto other random thumb drives because i only had about 250GB free on my external drive when i started downloading.
third. turn off your computer's ability to sleep. if you've got a pc that should be in the control panel under power settings. it should say power plan. my blog took about 15 hours to download. i had to just let my computer sit there downloading, and my computer needed to not go to sleep.
fourth, i would recommend using an ethernet cable if you have one. that will make it go faster.
you should get a file. though my computer literally choked on mine and i had to open it with 7zip because the zip file didn't quite work.
honestly if you're willing to spend an unreasonable amount of time and storage space on this i would recommend grabbing the tumblr native backup and then also using tumblr utils and scarping the text, then using the tumblr utils version of the text. my suspicion is that you can just grab the media folder from the tumblr export download and dump it into the tumblr utils folder and you'll be good. tumblr utils handles the text posts way better and more accessibly.
another space saving option is to just literally delete the media folder. or to delete the media in the folder that's not labeled "conversations," since the stuff labeled "conversations" is media that was sent in your dms and you may want to save that.
tumblr export WILL give you all you dms (including with deactivated users and users you have blocked and who have blocked you) and it will also give you unanswered asks (again including from deactivated users etc). probably also submissions and possibly also old fanmail, i haven't checked. i have not figured out yet whether you get your draft posts. if you do they're not in their own folder they're just mixed in with the rest.
the html formatting, however, is dogshit. even of the dms. the dm conversations are literally presented backwards.
