Benefits of optical media

Different types of data storages (HDD, flash storage, optical media) have their own sets of strengths and weaknesses.

Although the disadvantages of optical media (e.g. not nearly as portable as SD cards, speed limited by physical rotation speed, slower access times than HDDs and flash storage) are already well known, this article documents the benefits of optical media, many of which are unknown to most.

Longevity

⏳ Conventional quality media can be expected to retain full data integrity for at least ten years with normal storage conditions.

💽🕰 Specialized types of optical media are claimed to have a life span of over a hundred years (Verbatim Gold) and even a thousand years (M-Disc).

Although not verified in real-time, one can expect that media to easily hold data as long as needed by an individual.

Data retention

🛢 Flash storage is prone to data loss caused by electrical charge leaking out of the transistors, causing logical (non-physical) data errors to accumulate over time. This effect is called bit fading.

🛠 Data in a sector is beyond repair (also known as a bad block), if enough information is lost that the error correction code is no longer able to compensate for the lost information.

🗜 This problem gets worse with higher storage densities (e.g. high-capacity MicroSD cards with little physical space for each sector), worn flash storage (i.e. with fewer remaining writing cycles) and flash storage with low manufacturing quality (e.g. flash storage by vendor Hama). Heat does accelerate bit fading.

Solid state drives usually have a firmware that automatically refreshes the data in the sectors in background or when idle, to prolong data retention. However, many USB sticks and SD cards may not have such a feature.

🌟 In contrary, optical media is immune against bit fading and able to hold data until the end of its lifespan, after which not suddenly much or all data gets lost at once (like at a hard drive crash), but slowly only.

👀 In addition, damage to optical media (physical damage and disc rotting) is visible to the naked eye, and error correction code is able to retain full data integrity on optical media that is visibly damaged to some extent.

Error detection

Some USB stick and SD card models do not report bad blocks to the computer accessing the data and return damaged data as if it were healthy data.

Through optical media, the computer is always able to distinguish which sectors are damaged and which sectors are healthy.

Water resistance

💧 Although humidity reduces the long-term shelf life span of optical media, optical discs will gracefully survive an accidential splash in a pool without damage.

🌊💦 In case of a flooding natural disaster, whose likelihood depends on storage location, optical media has the highest likelihood of survival and is immediately functional (readable from an operational disc drive after drying the disc) if it is not physically damaged, while non-sealed flash storage and hard disks have the least chance of survival and are not operational in case of water ingress.

Predictable failures

Error scanning

🔮🔎📊 With tools such as Nero DiscSpeed (Windows only) and QpxTool (cross-platform), failures (bad blocks) caused by disc aging and accelerated failure of low-quality media can accurately be detected years in advance.

In contrary, failures on other types of data storage devices such as flash storage (USB, SSD, SD cards) and hard disks are less predictable. S.M.A.R.T. is only a rough measure for detecting failures, and one should have backups anyway.

Planned obsolescence immunity

While hard drives can deliberately be built to mechanically fail prematurely or shortly after expired warranty, and flash storage even is far less predictable, optical media can not have hidden planned obsolescence built in.

If a specific optical disc is of low manufacturing quality, thus not expected to retain full data integrity for a long time, error scanning would measure a high error rate immediately after the disc has been written to.

Safety

No malicious hardware

⚡ Malicious hardware such as so-called rubber duckies which can hijack devices (for example, by pretending to be a keyboard and act maliciously disguised as human input), and USB killers which may even destroy devices, can be disguised as any USB peripheral, including input and storage devices.

Optical discs however can not contain malicious hardware, yet they can simulate flash storage.

EMP-proof

Optical media has a much greater resistance to electromagnetic impulses (EMP) than flash storage (e.g. SSD, USB sticks, SD cards) and magnetic storage (e.g. HDD, LTO tape).

Data on optical media could only be damaged from heat produced by electromagnetic waves (e.g. in a microwave), not from electrical currents in the circuitry (flash storage) or destruction of magnetic field arrangements (HDD).

Reliability

Optical media has a higher fault tolerance than hard disk drives and flash data storage.

An optical disc itself contains no mechanical components or electrical circuitry that can fail.

If an optical drive does not function properly, the disc can be retrieved using the emergency ejection pinhole (on the commonly used tray-load drives).

Electrical

⚡🔏 Existing data on optical media can not get damaged by so-called brown-outs, which, in a nutshell, is a temporary malfunction of a microcontroller caused by a voltage that is too low for proper operation, but not low enough for complete power-off. Such issues may be caused by an unstable voltage from a damaged power supply.

Although flash storage is the most vulnerable storage type to brown-outs, well-designed circuitry should be capable of handling it without data damage.

Mechanical

⚙ In case an optical drive would experience a mechanical failure, which is far less likely than on hard drives due to less delicate components, the disc would just stop spinning (as opposed to a possible hard drive head crash that would physically scratch the spinning disk) and be gracefully recoverable through the emergency ejection pinhole of the optical drive.

Hard drives can usually only operate at the fixed speed they were designed for (e.g. 5400 rpm, 7200 rpm), while optical drives can spin at any speed below the maximum speed for read access. Some optical drives allow read access during disc acceleration. Supported writing speeds of optical media depend on the supported speed range of the media type. The range of speed is wide for write-once media and narrow for rewriteable media.

Price per piece

💰 For offline (hard-copy) distribution of data, optical media has, by far, the cheapest prices per piece.

🛢️ One disc costs less per piece in larger spindle packages such as 50 and 100 discs.

📶🚫🇮🇷 In conutries with poor speeds and availability of Internet, such as Iran, optical media is a popular medium for file sharing.

True write protection

✏🔐 A disc that is non-(re)writeable, finalised or accessed through a -ROM (read-only) disc drive is immune against writing access. Therefore, malicious software (malware) would be unable to cause damage to the data or spread through optical media.

🔓 Although it can also prevent accidential write access by the user, that can also be achieved by mounting the file system as read-only, but only if supported by the operating system.

💳 The “write protection” feature of SD cards is less reliable than the write protection of optical media. Although SD cards and MicroSD-to-SD card adapters have a write protection slider, it depends on the SD card reading hardware to obey the write protection, which is not always the case.

Power surge immunity

⚡ A power surge caused by a lightning strike, malfunctions in the power grid or power supply unit, or malicious hardware (i.e. so-called USB killers) could immediately render attached flash storage defective and destroy the data on them.

🔬 Hard drives may be recoverable using laboratory forensic tools after a power surge that destroyed the control circuitry, if no physical damage has been induced onto the metal plates which store the data.

📎 A power surge might as well destroy the circuitry of an optical disc drive, but the media itself can gracefully be recovered using the emergency ejection pinhole of the disc drive and then retrieved through an operational disc drive.

Magnetic immunity

🧲 Data storage technologies that rely on magnetic technology for reading and writing (e.g. hard disk drives, LTO tapes, floppy disks) are more or less prone to interference by external magnetic forces.

Whether during operation or not, excessove magnetic forces could damage data on magnetic data storage devices. Therefore, such devices should not be stored in the proximity of magnets.

Although excessive magnetic forces might interfere with the operation of an optical drive, the optical media itself is completely immune to magnetic forces.

Long-term exposure to magnetic forces can not damage data stored on optical media.

As a reference, flash storage is able to withstand strong static magnetic fields, but is vulnerable to quickly changing magnetic fields due to electromagnetic induction.

Random access

All optical media supports random access reading. Some types also support random access writing.

This is a benefit of optical discs compared to linear tape storage, another archival option with high reliability and shelf life span, higher data density and lower price per unit (note: but LTO drives are very expensive), but no random access ability.

Safe ejections

See also: Loading mechanisms of optical drives

Drives with a tray loading or slot loading mechanism can be locked by the computer to prevent unexpected ejection during write access and with unfinished UDF session which can be finished prior to ejection upon pressing the ejection button on the optical drive.

In addition, optical discs are immune against loose contact issues known from USB sticks and SD cards

The spinning sound from an optical drive does accoustically signal the user that it is currently in use. The disc is internal and does not stick out of the device like USB sticks do.

The LED I/O indication light usually blinks slower during write access than during read access. The behaviour and blinking pattern of the LED indicatior lamp varies between vendors of optical drives.

Benefits at time of release

This section documents benefits of optical media at the time the disc type was released to the market.

Random access

📼 A significant benefit of any spinning disk medium (optical, HDD, Vinyl) over linear tape storage (e.g. MiniDV, compact audio casettes, VHS, etc.) is the random read access ability.

🎞 This meant that any content on audio CDs, Video CDs (those using MPEG1), Super Video CDs (those using MPEG2) and DVDs was accessible within seconds without the need to fast-forward or rewind until reaching the spot, as needed on the then popular video casettes and compact audio casettes.

📹 Miniature (8cm diameter) recordable DVDs were also used as an alternative to MiniDV casettes for camcorders in the early 2000s, both of which have been succeeded by camcorders using SD cards.

High speeds

🌠 At the time of release and popularization of CD-ROMs and DVD-ROMs throughout the 1990s, optical computer drives reached transfer speeds upwards of hundreds of times faster than the average Internet speeds and the speed of floppy disks.

High capacities

💾 In the 1990s, floppy disks were commonly used for transferring data between computers, later succeeded by flash drives.

But floppy disks were heavily limited in capacity and speed, and other proprietary media types such as Iomega Zip disks brought a risk of vendor lock-in.

🖥 The capacity of CDs and DVDs in the 1990s often exceeded the internal hard drive capacities of computers.

Digitalness

Data portability

💻 Data stored on CDs, DVDs and BluRay discs can directly and quickly be retreived and backed up using a computer equipped with an optical drive (built-in or external).

📀💿 Even the latest BluRay drives are still backwards-compatible to the earliest CDs.

In comparison, data stored on analogue media (e.g. tape) needs to be played back at original speed (×1) through an analog-to-digital converter connected to a computer. There is a slight loss of quality in the process.

Lossless retrieval

✨ Data stored on intact digital media can be read and replicated (copied) indefinitely without loss of information. Error correction mechanisms ensures full data integrity despite damage to some extent.

🧿 A common problem with analog media such as compact audio casettes, video casettes and vinyl has been the slight degradation of quality and wear-down after each reading cycle due to friction from the reading head.

♻️📑 Analog media (non-digital magnetic tape storage and also paper) also suffers from generational losses, which means that a copy has a slightly lower quality than the original, of which the quality loss would accumulate over time after each level of copying (copies of copies).

🔦 Because data from optical media is retreived without physical contact by the reading head to the disc, but with a laser beam instead (hence optical media), data from optical discs can be retreived an indefinite amount of times without directly slightly damaging it.

Non-technical benefits

This section documents benefits of optical media that are outside of technical nature. These benefits vary based on user perception.

Nostalgia

Similar to Vinyl records, optical media provides a sense of nostalgia to some users.

The rotation, if visible, could provide additional visual feedback of music playback.

Physical substance

When stored on flash storage, the data exists in the form of charged nanotransistors.

On optical media and vinyl, the data (i.e. music) is physically engraved on the media.

Sense of assurance

The high fault tolerance and true write protection ability of optical media provides the user with a sense of assurance and freedom from potential random unexpected failures.

Sense of stability

Data written on optical media is more engraved than e.g. on a hard drive or USB stick.

Write-once media provides true protection against overwriting, and even overwriting data on rewriteable media takes much more technical effort (bundled laser beam heating up the phase change material to hundreds of degrees of a short moment) than reprogramming transistors in flash memory or altering some magnetic fields on the rotating disk of a hard drive, which provides a sense of stability.

Sense of appreciation

One can have a sense of appreciation on how the optical drive works under the hood to read from the disc and deliver the content.

Some might feel a sense of enthusiasm from the engine sound of optical drives operating at high speeds, that resembles what automotive enthusiasts perceive from vehicles.

Sense of ownership

Although 2020s Internet bandwidths enable streaming videos in high qualities to more users than ever before, offline media provides a sense of assurance that the data (e.g. a movie) is always accessible and not prone to potential technical issues of the streaming provider and the Internet service provider.

Bonus material

Movies on optical media often contain bonus materials such as insights behind the scenes (making-of's), exclusive interviews and commentaries.

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Also see

• Observations on optical disc drives
• Loading mechanisms of optical disc drives

Related navigation boxes: Electronics • Mobile phones • Data storage • User experience and user interfaces

External links

• Essay on the benefits of optical media on Poal.co
• Answers to “Why do people still buy CDs?” on Quora
• IBM Artillerie about the benefits of optical media.
• Wikipedia article about optical media preservation
• Independent test of quality degradation of conventional media vs. quality media (Maxell ProTek) under sunlight exposure over months.
• Optical media white papers 📑📄 by Pioneer Electronics (2001)
• Article about optical media on DailyBrandStory.com.
• Article: “Sony Buys a Facebook Spinoff to Give New Life to Blu-ray” – WIRED.COM (2015-05-27)
• Video: DVD: The Death Knell of Laserdisc [26m12s] – Technology Connections (2018-03-18)

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