Why 90s PCs backed up data on audio cassettes
Backing up your data on what looks like a weird VHS seems crazy in 2026, but it was the reality for years. In many offices and studios, making backups literally meant swapping out a small cartridge and hoping for the best.
Some of you may remember, some of you don’t, but I’m talking about DAT (DDS). Let’s talk about what it stored, why it wasn’t commonly used by home users, and what made it special.
Tape backups were real, and they were everywhere
Even though now they are nowhere to be found.
Yeah, that’s true. Not that long ago (well, the 90s and 2000s, so quite a long time ago actually) you could back up your data to tape. DAT (Digital Audio Tape) and DDS (Digital Data Storage) tapes have been found in many offices, studios, schools and server rooms. Not so much at home, but more on that later.
The name is a bit confusing, especially for DAT files, because how can you save the appropriate data from a PC to what is called an audio tape? DATs were a 4mm cassette format originally designed for audio recording. Meanwhile, DDS tapes used the same cassette style and tape technology, but wrote computer backup data, not music. The names get mixed up, but DDS was the correct term used in the context of PCs.
In practice, a DDS setup was a tape drive connected to a PC or server, often via SCSI in those days. The backup software ran on a schedule, wrote the data to tape, and recorded whether the job was completed or not. This was often done overnight and in the morning someone’s job was to eject the cartridge, label it, and insert the next one.
These tape backups seem strange in today’s PC climate, but at the time they made sense. They were inexpensive to maintain, easy to store and take off-site (a real problem in those days without cloud storage). A tape cartridge was small, light and far from demanding. It also created an offline copy by default when ejected, which protected these saves from common save problems, solved today by the 3-2-1 save rule.
What DAT (DDS) is actually stored?
These safeguards were different from those we face today.
It’s not like these backups are the equivalent of an entire PC’s data cloned onto a cartridge. In most cases, users create a backup set using dedicated software. This software determined what to copy, when to copy it, and how to keep an eye on it for potential restorations. The tape was just the destination.
Most companies used these tapes for full and incremental backups. A full backup would be, well, complete, meaning everything you had selected at the time. Nightly increments only recorded what had changed since the last save to avoid doubling. Otherwise, companies would be burning tapes at an alarming rate if they wrote a full backup every night (not to mention it would also take a long time).
Tape backups were also software driven and cataloged, because tape is sequential. The backup program kept an index of what was on what tape and where it was located on the tape, so it could restore specific files without you having to search for them manually.
Another strange thing about these DDS tapes was that the advertised capacities were often formulated around compression assumptions. The backup software compressed the data as it wrote it to tape, so you would see native and compressed numbers, and often a significant gap between the two.
Why DAT Backups Were Not a Solution for Home Users
It wasn’t impossible, it just wasn’t popular.
You may notice that I’ve mostly talked about DAT/DDS backups in the business context. This isn’t because these backups wouldn’t work at home; it’s more that they weren’t an obvious choice.
Disks were expensive relative to what most people were willing to spend to protect their data, not to mention that back then many people weren’t as concerned about backups as they are today. Costs aside, installing the DDS hardware wasn’t exactly plug-and-play. Much of it relied on SCSI, which, in turn, required additional hardware and drivers. This was a problem for the average home user.
Beyond that, it didn’t help that the tape was sequential. It’s not like you can easily go through your backups, zero in on the exact file you want, and restore it. It’s more like rewinding a VHS tape; there was no faster way to do it, you just had to sit still.
The restoration process was also heavily dependent on the backup software working properly. Without this catalog, restorations could become painful, as the player may have to go through large portions of the tape to reach the correct segment. It’s a tolerable nuisance if you’re paid for it, but not so much when you’re just trying to save some files in your home setup.
The modern version of the idea of the band
Have all DAT/DDS tapes been lost over time?
So, have you ever backed anything up to tape? And if so, has it been in the last 20 years? I guess not, but feel free to surprise me. DDS tapes no longer exist, either in the consumer or professional market, but tape backups still exist.
The format you will hear about today is called LTO. These backups still belong where they matter because they offer high capacity per cartridge, low cost per terabyte stored over time, and easy off-site storage. Tape remains a simple, straightforward and familiar way to keep large, cold archives.
For most of us, the idea of the tape (with a hint of nostalgia) survived even though the material was totally obsolete. The closest equivalent to a fully offline copy that you would physically delete from the system are immutable backups, offline backups, and versioned backups. This can be achieved with things like an external drive, including an SSD in an enclosure, a NAS that takes snapshots that you can’t easily rewrite, or a cloud backup service with long retention and recovery.
What about those old DDS tapes? I would say they are lost to time, and for some boring reason. You may still have the tapes, but the drives that read them and connect them to your PC are hard to find. You need more than just hardware; you also need the right interface to connect it, and that’s simply not the case on modern PCs. But looking back, it’s fun to remember that there was a time when tape backups were actually quite common.
