I know my comment won't move this discussion forward in any fashion, but I have to ask anyway.

What was this data, and why did they feel they needed to keep it?

I mean - 300PB is nothing to sneeze at. I can understand wanting to keep important data around (IP, for instance, or recent server logs for the last 30 days or even a year) - but this amount seems to go well beyond that.

In fact, it almost seems like they have stored every single tweet ever written. In addition to probably all of their logs, and who knows what else.

Why are they keeping all of that information? If it is all the tweets ever written - they don't have copyright to it, so such information wouldn't belong to them...

I'm not a big twitter user - can I search for a tweet on their system that I (or someone else) made say...5 years ago or longer? If this is a bunch of tweets - is that why they keep them around?

Are people in general aware of this? That is - if they are tweets - that Twitter has stored all of them, forever and ever, and that they are all still accessible (if not by the general public, then by law enforcement at the very least)?

If they are tweets - do users have any recourse at being able to remove those tweets (aside from those that they likely are legally bound to keep - I am thinking of the current POTUS's tweets, for instance)?

What is the ultimate purpose behind keeping all of that data? Even if it wasn't a bunch of tweets, whatever it is can't really be that useful otherwise, except for maybe the most recent stuff created in the past year, at best. Things like that - logs, etc - might be destined for a rotated "cold storage" and would ultimately "age out". Accounting records (financial data, etc) probably isn't that great a percentage of the data (if at all?) - but whatever was there, too, would likely need to be saved for a greater range - but even there maybe only 10-15 years worth (and it certainly wouldn't even comprise a fraction of the bulk).

So what is it? Why is it being kept? To what purpose? While 300PB isn't that great of an amount in physical terms (that is, the storage medium probably doesn't take up a great amount of space in a datacenter), it still isn't anything tiny, either (especially depending on what medium was used - I mean, I doubt they are storing it all on a ton of 256GB microSD cards - though that does bring up an interesting idea/thought to mind - but I digress).

I'm of the thought that companies shouldn't just "throw away" data - but it should be tempered by "importance to humanity over time". Not everything should be kept - but, for instance, it would have been nice if we (humanity) had kept around the original transmissions from the surface of the moon, or the blueprints to the rocket that took humans there. But we probably don't need all the various interoffice memoranda and fluff at the various NASA contractors (we probably don't need the accounting records - but BOMs might be useful).

That's just a couple of examples I can think of off the top of my head, but history is rife with instances of companies imploding or being bought out or restructured in such a manner that data is just "destroyed" instead of kept. Or lost, or otherwise made unretrievable to humanity.

Here with Twitter - an active company to be sure - we have the seemingly exact opposite - almost like r/datahoarders were in charge.

...and that should concern people a bit, regardless of which company it is - but especially a company like Twitter.