Before cartridges, hard drives and the cloud, businesses, universities and government agencies stored their data on big open reels of half-inch magnetic tape. Many of those reels are still sitting in storage rooms and archives today, holding decades-old financial records, research data, engineering files, census and payroll records, and source code.
Getting that data back is possible, but reel-to-reel data tape is one of the most challenging types of recovery there is. Here’s why, and what you can do to give your reels the best chance.
This post is about computer data tapes on open reels, such as 9-track and 7-track tapes from mainframes and minicomputers, not audio reel-to-reel recordings.
What are reel-to-reel data tapes?
From the 1960s through the 1990s, the standard way to store and exchange computer data was half-inch tape on open reels, often up to 10.5 inches across. The most common type is 9-track tape, used by IBM mainframes, DEC, Unisys, Honeywell, Data General and many other systems. Older systems used 7-track tape.
A single reel might hold anything from a few megabytes to around 170 MB, depending on how densely the data was recorded. Typical recording densities were 800, 1600 and 6250 bits per inch, each with its own encoding method.
Challenge 1: Finding equipment that still works
Reel-to-reel tape drives haven’t been manufactured for decades. The drives that still exist need careful maintenance: worn heads, dried-out rollers, failing vacuum columns and aging electronics all have to be dealt with before a drive is safe to use on irreplaceable tape. A drive in poor condition can stretch, crease or scratch the tape on the very first pass.
The drive also has to match the tape. A drive that only supports 1600 bpi can’t read a 6250 bpi tape, and 7-track tapes need a 7-track drive.
Challenge 2: The tape itself is aging
Magnetic tape was never designed to last 40 or 50 years. Common problems include:
- Binder breakdown (“sticky-shed syndrome”). The glue-like binder that holds the magnetic coating absorbs moisture over time. The tape becomes sticky, squeals as it runs, and sheds its coating onto the drive heads, taking the data with it. Specialists can sometimes stabilize these tapes temporarily with a carefully controlled treatment, but it must be done correctly or the tape can be ruined.
- Brittle or warped tape. Very old tapes, especially those on an acetate base instead of polyester, can become brittle and snap.
- Mold and moisture damage from damp basements, flooded storage or poor climate control.
- Physical damage: creased or crinkled tape, damaged edges, loose or unevenly wound reels, and cracked reel flanges.
- Missing leaders or markers. Drives look for small reflective markers near the start and end of the tape. If these have fallen off or the start of the tape is damaged, the drive may not load it at all.
Some aged tapes may only survive a single read. That’s why the first goal in any reel recovery is to capture a complete raw image of the tape in one careful pass, before anything else is attempted.
Challenge 3: Knowing what’s on the tape
Reel labels are often faded, handwritten or missing entirely, and the people who created them have long since moved on. Before the data can be read correctly, a recovery lab has to work out:
- Whether it’s a 7-track or 9-track tape, and at what density it was recorded
- Whether the tape has standard IBM or ANSI labels, or is unlabeled
- How the data is broken into blocks and records, and where one file ends and the next begins
- Whether the tape is part of a multi-reel set, and in what order the reels belong
Challenge 4: Turning raw data into usable files
Reading the tape is only half the job. The raw data from a mainframe tape usually isn’t something you can open on a modern computer:
- Different character sets. IBM mainframes store text in EBCDIC rather than the ASCII used by modern systems, so text has to be converted.
- Old data formats. Records may contain fixed-width fields, packed decimal numbers from COBOL programs, or binary values that need a record layout to interpret.
- Proprietary backup formats. Many reels hold system backups or dumps rather than plain files, written by the operating system or backup utility of the time, and these need to be decoded.
Any original documentation, such as record layouts, program listings, or notes about which system created the tapes, can make this stage much faster and more accurate.
What you can do to protect your reels
- Don’t try to play them on an untested drive, or “just to see if they work.”
- Store reels upright (on edge, like records) in a cool, dry place away from heat, sunlight and magnetic sources.
- Don’t open, rewind, or re-wrap the tape by hand.
- Leave write-protect rings out. On 9-track reels, a plastic ring on the back of the reel allows writing. Without it, the drive can’t write to the tape.
- Keep reels in their original cases and sets, and don’t separate multi-reel sets.
- Photograph the labels and collect any paperwork: system names, dates, job names, record layouts and old manuals.
- Act sooner rather than later. Tapes and working drives only become rarer and more fragile over time.
How Disklab can help
Disklab recovers data from 9-track reels and other legacy tape formats, alongside modern LTO, DLT and DAT cartridges. We start with a free evaluation, provide a file list after the recovery is completed so you can confirm what was recovered, and deliver the data on modern media or securely online. If you need your archive moved off tape for good, our data migration service can help.
Have a box of cartridges instead? Read Found Old Backup Tapes? How to Find Out What’s on Them.
Have old reels that need recovering? Start a recovery case or call us at 1-844-347-5522. The evaluation is free, and you pay only if we recover your data.