Open Reel Tapes
9-Track and 21-Track Tapes
9- and 21-track tapes represent the start of commercially available data storage media. General consumers could purchase 21-track tapes in the mid-1960s and 9-track tapes a few years later.
Since their release, businesses in banking, insurance, oil and gas, and other batch processing sectors, have used millions of the tapes to store important data.
Arguably the largest user of 9 and 21-track tape media is the oil and gas industry for geophysical exploration data. Throughout the 1960s and 1970s, the oil and gas industry recorded large seismic surveys worth millions of dollars on these tapes.
Stiction
Over time, manufacturers increased the data capacity, length, and recording density of their 9 and 21-track tapes. In the early 1980s, manufacturers tried to maximize the capacity of a single reel by producing thinner tape, allowing more tape to fit onto each spool. However, this change in production methods had an unexpected outcome.
The result, known in the industry as “stiction” (sticky friction), occurs when the oxide on the tape becomes sticky and fragile with time. If not managed properly, this condition can lead to irreversible data loss.
Closed Reel Tapes
8mm Exabyte
Exabyte is the original brand in high capacity 8mm tape storage technology. In the late 1980s, Exabyte Corporation introduced helical scan recording technology, which quickly gained recognition as a reliable and cost-effective format. It offered high-speed read/write capabilities and a wide range of native capacities and formats.
The Exabyte 8mm data storage tape marked the first use of helical scan recording technology for data storage purposes and was mechanically identical to the widely used 8mm video format technology found in the professional media and broadcasting industry. Exabyte 8mm technology shares similar mechanical components found in home video systems because of its heritage with Sony.
Helical scan technology uses a rapidly rotating read/write head to record data onto a slow-moving magnetic tape. It records the data onto diagonal tracks that angle toward the edge of the tape. Once inserted into a drive, the tape is pulled from the cartridge and wrapped around the read/write head, which rotates at approximately 30 meters per second. The Sony AIT family also uses the same 8mm technology.
The helical scan 8mm technology led the market for a time because of its data transfer rates of around 240KB per second and initial storage capacity of 2.4GB. However, it has since been surpassed by linear recording technology. The newer linear recording technology allows for faster reads and writes, lower search latency, and is the technology that all sectors of data storage ultimately adopted.
What is Linear Recording?
Linear (or longitudinal) recording is a method of recording data whereby tape is passed by a non-moving recording head. The tracks are recorded parallel to the tape edge.
Why Migrate from Exabyte 8mm Technology?
Exabyte 8mm data storage technology has now reached end of life (EOL). Although designed primarily for the domestic camcorder market and not the commercial data storage market, the Exabyte format became incredibly popular in the commercial sector in the 1980s and 1990s because of its relatively low-cost drives and tape media. As a result of this popularity, a broader, more comprehensive adoption of the technology occurred than perhaps strategically suited the technology. Only in recent years as the technology neared EOL have many clients found its early economic advantages overshadowed by decreased reliability and data loss.
This type of aging 8mm tape is now becoming the new legacy migration requirement. Unfortunately, it also comes with new problems that can make it difficult or even impossible to recover the data.
Traditionally, 9-track tapes presented problems for data transcription. However, with the implementation of binder hardening processes, specialist software, and multiple reads of exercised tapes, the data in 99% of these cases are recoverable. Data stored on 8mm technology may not be so lucky. From our experience, we find there are many factors that put data stored on 8mm technology at risk.
Tape Width
With the exception of 4mm DAT tapes, Exabyte 8mm tape technology is the narrowest data storage tape introduced to the market. In comparison, most of the tape in today’s cartridges is 25mm. The narrowness of the tape makes it weaker, increasing stress and damage over time and multiple physical tape loads.
Dual-Reel Architecture
The dual-reel cartridge architecture of the 8mm Exabyte technology is not ideal. The complexity of the configuration makes the tape more susceptible to physical defects and looping within the spools. This in turn causes inconsistencies in the tension of the media and the potential for damaging creases, nicks, and folds. The tape can also be crushed, stretched, and snapped. Closed cartridges in this format result in a “if you can’t see it, you can’t fix it” scenario. The now more commonly implemented open reel architecture used with LTO and 3590 media overcomes the difficulties inherent in closed reel forms.
Limited Head Adjustments
8mm Exabyte tape drives are limited in the number of head adjustments that can be made while reading data. If there was a skew of any kind on the original drive that wrote the data, and the skew cannot be replicated by a head adjustment on the new drive, then it is unlikely the data can be recovered. In addition, multiple readings of the tape at different head settings and the constant stopping and starting can cause stress on the tape and result in snapping or damage.
Internal Drive Settings
Some 8mm Exabyte drives featured internal settings that allowed users to create different partitions within a tape cartridge. Often these settings were specific to organizations or departments, and this information is not easy to find or second guess during a recovery or migration.
No Longer Supported By Manufacturer
Exabyte 8mm technology is EOL and is no longer supported by the manufacturer. In fact, Tandberg purchased Exabyte in 2006. This means that there are no new drives available for purchase, nor spares readily available for maintenance and repair of existing drives. From our own experience, even purchasing older working drives is becoming increasingly difficult.
Type of Data Held On Exabyte Technology
Using the oil and gas industry as a prime example, the type of data stored on Exabyte 8mm technology was largely processed data. This means that substantial value was added to the raw data, and even small losses of data can be significant.
Density
Exabyte tapes have low density in comparison to data storage technology commonly used today. An average holding of 1,000 Exabyte cartridges would now easily fit onto 3 or 4 LTO tapes, which in addition to the main advantage of data security and longevity, also represents savings in ongoing storage and retrieval costs.
Brand Differences in Media
Largely because of the manufacturing process of 8mm tape and how the end products were distributed for re-badging and re-sale, there are significant differences in the reliability of different media brands. The brand of media used for storing your data should be an important consideration when planning for its migration to newer technology – with the inferior cartridges taking priority when possible.
DLT Cartridges
DLT technology was a robust, mid-range data storage technology known for its stability, durability, and scalability. Having reached EOL some time ago, it is now outdated, and its once-noted reliability is faltering.
DLT retired drives are now often unreliable and prone to physical damage and stress. DLT is a low-capacity legacy technology, and data stored on DLT cartridges are now considered “at risk.” We recommend immediate migration to a higher density, more stable data storage technology to ensure data preservation and accessibility without data decay.
3000 Series Cartridges
Overall, the 3000 series (including 3480, 3490, and 3590) linear tape media types are robust and have stood the test of time. The main concerns for this media type at this time are the availability of hardware to read the tapes and density variations between tapes.
Generally speaking, the 3000 series media demonstrate high recoverability when compared to other media types such as 8mm Exabyte, 4mm DAT, and DLT. Some of the main reasons rest with the fact that IBM was the core engineering body behind the 3000 series hardware. IBM have a track record of producing robust and reliable recording hardware, media, and format specification.
We have found that storage conditions, however, will play an important role in the readability of the media.
During the past few years, we have encountered many read issues with 3480, 3490, and 3590 cartridges. In one case, approximately 3,000 3490 cartridges from a survey recorded in 1995 were almost unreadable.
To add to the above, no manufacturers are making the tape drive heads for the 3480/3490 tapes. Hardware is nearly impossible to find.
Unparalleled Experience in Tape Transcription
Ovation Data has recovered data from millions of tapes. To ensure high quality recovery and transcription, we developed an advanced workflow that has proven to be one of the most effective means of carrying out this work. In addition to our procedures, we also use our own custom software, developed to handle many of the complex issues touched upon here. Contact us to help with your tape transcription needs.
