Tape is the only commercially-available storage medium that can be used for long-term archival storage, e.g. 10 years or more. The tapes are typically specified for 30 years storage time, but it is likely that you will have to transfer the content on larger tapes earlier than that or you might not be able to find compatible drives.

Nonetheless, a 10 year storage time is easily achievable with tapes.

There are no competitive devices. The optical disks have a far lower capacity. Moreover, except those made with gold, which are no longer produced, the metallic mirror will oxidize after a few years and the disk will become impossible to read. The SSDs and other flash-based devices lose the charge after a few years. The HDDs that are not in active use will develop after a few years mechanical problems and they may remain stuck.

There are other technologies that could be used to make memories suitable for archival purposes, but nobody has tried to develop commercial products. The market is small, because most people do not think much about the future so they discover that they should have spent more on archival storage only after some precious data is lost and it can no longer be retrieved.

In my home, I am using LTO-7 tapes to store data whose loss I consider unacceptable. For example, because of space problems, I have scanned a huge quantity of books that I had previously, then I have destroyed or donated the paper copies. Since now I only have the digital copies, which are much more prone to irremediable loss than the paper books, I take serious precautions to avoid any such loss, e.g. for each file I store copies on 3 tapes, which I keep in different locations.

Well, maybe.

We use LTO6 to backup daily 60tb of data from production, so ten tapes a set. 14 dailies, 13 monthlies, and 7 yearlies.

We are probably moving to a Data Domain solution; as in spinning disk; but the key to archival security is that backups are replicated between two sites that are geographically separated. space usage is minimized by compression and logic that can treat newer backups as extensions of existing data rather than duplicating all the data again.

the big advantage is restore speeds. spinning up ten tapes which we write simultaneously because of speed needs is cumbersome and slow with restoring a single table taking nearly half as long as the actual backup. On a DD system its less than 30 minutes and with backups replicated to both centers a restore can be done to production that was saved from the dr site; we replicate from production to dr and only backup dr daily.

the issue with tapes has been you never know when the one you need is gone bad until you need it. it is also not common to replicate tape sets but a disk base solution lends itself to easy replication and transmission from site to site.

so I can see both solutions working side by side for some companies but for many the disk based backup solutions that are out have come down in price; most are leased; as storage devices have dropped.

are biggest limitation still is the number of ports between system and backup devices.

> the metallic mirror will oxidize after a few years and the disk will become impossible to read.

I think NIST or somesuch did accelerated decay studies and found even moderately decent storage conditions for plain DVD-/+R was 30 years, with BD-R in the same conditions being vastly longer than that. I do know that i have 20+ year old CD-R backups* that still work, and as far as i can tell all of my DVD backups from 2002 and on still work. I recently got some 100GB BD-R but haven't written them yet, my laptop doesn't have enough storage for windows to do its thing, and i have 0 idea how to do a bd-r "files" backup on linux. Every google result is "how to back up your blu-ray movies" which is explicitly not what i want to do.

* I also had a DVD-RAM drive in 1998/1999, with the "caddy" cartridge, and probably still have a couple of those discs, unsure if they work/if i can read them.

It is true that there are optical discs that will survive for a long time, because the plastic coating of the metal has a low enough permeability to the oxygen from the air.

The problem is that as an individual, it is impossible to guess whether the discs that you have bought are good and they will last 50 years or they are bad and they will last only 2 years.

There have been many published cases when the lifetime claims made by manufacturers were proven to be false.

The reason is that it is difficult to control the permeability of the coating during production. While many discs may be good enough, there are also many that will have a short lifetime.

The risks of storing data on standard optical discs are too large to be acceptable. There were special archival-quality optical discs with gold reflective layers, e.g. made by Kodak. Those could really be guaranteed for 100 years or more, but they were too expensive, so they were discontinued.

I mourn the death of optical disk, back in the primetime of DVD they were actually viable for backups of personal photo libraries and the likes.

I even had a special printer that would put a custom image on the face of the disk!

Gosh I miss the old MAM-A gold DVDs. Are there none left?

Just geometrically, tape will be king for ... quite some time.

Imagine a HDD platter. You can only write to the surface of it. That's a small surface area, when you think about it. Now imagine the surface area of an unspooled tape ...

Of course, SSDs are a different beast but they are nowhere near as dense.

The spooling and unspooling for the geometric advantage is a tradeoff between time and space. Therefore, tape will continue to reign supreme for colder backup up until such time as some kind of holographic, volume-penetrating technique reaches the sheer density of a wound tape, adjusted by some kind of time factor for the read-write of our hypothetical holocube.

tape is still king of long term or cold backups. most people also keep hot backup on hdd or ssd in addition. but there are usually off prem long term cold storage backups along with these and those are very often tape. these tapes are for like FUUULLL dr and not often used but kept as insurance against the hot short term backups getting hosed

MicroSD cards are nowhere near reliable enough to stripe a petabyte of data across them. At current prices it would also cost around $120,000 + the cost of the readers and the robot to swap them around.