Optical Discs Should be a Serious Contender for Storage
Optical discs seem to be coming to an end. Many laptops are now shipped without optical drive. People just don’t seem to be burning optical discs anymore. Many regard optical media as something of the past. Yet are they?
Magnetic Storage Device – Too Fragile
In the digital age, few media can be considered reliable for safe data storage. Magnetic storage such as tape device or even floppy disc are prone to moisture and other environmental factors. While they seem to be the logical and relatively economic media for cold storage, they’re also highly fragile. Magnetic data fade with time, and the tapes are prone to fungal attack. Disasters like hurricane or flood will ruin the media and the data would be lost forever. That was what happened with Katrina in the U.S.A. and tsunami in Japan not so long ago. Data stored in the magnetic storage media simply could not be recovered. Plus, magnetic tapes are probably only good for backing up the data fully in one go, because they have no random access and are a frustration when you only want to access some of the data on the tape.
Flash Device – Not Durable
Flash devices are also unreliable. Compared to hard disks, they’re relatively short-lived. They do not have “bad sector” where only part of the data is lost. Once they’re down, they’re completely down. Although they can be specified to be able to read/write up to 100,000 times, real-life tests show that they don’t even last half that long. The same very much goes for solid-state disks (SSD). They offer great performance but they’re less on their reliability.
They’re not good for long-term cold storage, either. They’re expected to last 5~10 years without further power supply, but sometimes they do not last that long. To replenish the capacitors which store data, you have to run through every storage bit. I have more USB drives broken than working, and they’re all within 5 years old.
Hard Disks – Convenient but Guaranteed to Fail
Hard disks are extremely high-precision machines that are also highly sensitive to the environment. The disks themselves are an engineering to marvel at. The most common spin rate of hard disks is 7200 rpm (revolutions per minute), and it already poses a great centrifugal force to work against. Lower energy-consumption HDD’s (hard disk drive) have 5400 rpm. High performance HDD’s have 10,000 rpm or even 15,000 rpm. The disks used to be metal, but metal expands with heat, so modern HDD’s all use glass as their substrate. Glass has minimal heat expansion and can have an extremely even surface, making it the ideal material. However, glass also makes HDD’s highly susceptible to impact. The disk literally shatters inside the metal casing.
Another susceptibility of hard disks to impact is the read/write head. The read/write head rest has two designs: a non-recording surface on the inner area of the hard disk to rest the read/write head on, or a ramp outside the rim of the hard disk to rest the read/write head. Few HDD’s offer the first design today. Ramp technology is the norm. The read/write head moves over the entire surface of the hard disk. Despite the fact that HDD’s use magnetic storage technology, the read/write head doesn’t actually touch the surface of the disk. The hard disk generates air turbulence when spinning, and the read/write head is designed so that it rides on the airflow and floats just above the HDD. The floating height is so minimal that even a slight dust found on the hard disk will cause major collision at operating speed, creating scratch on the hard disk, thereby damaging it. If the read/write head is working on the surface of the disk, and it suffers a slight nudge, it may accidentally come in contact with the disk and scratch it.
These are but some of the mechanical issues that can cause an HDD to fail. There are also electronic problems such as power surge, etc. Data are often not lost because of mechanical malfunction or even electronic malfunction, but become inaccessible, and access to data on a broken HDD is a highly professional skill that is also very expensive. No layman without the right environment, equipment, and knowledge can recover data from a broken hard disc, because the slightest dust on the platter will make the HDD fail.
The mechanism will wear out, usually in 5 to 10 years, sometimes less. HDD’s are guaranteed to fail the moment they are used. Electronic components are also guaranteed to fail by themselves even if they are not used. In other words, despite how much storage HDD’s offer, and how convenient they are, all of them are doomed to fail in a matter of years.
Recordable Optical Disc
There are mainly three types of recordable optical discs: CD-R, DVD±R, and BD (blu-ray disc).
Recordable optical discs are much simpler than the hard disc drive. They use special photosensitive dye on their recording surface, which changes color when it comes in contact with laser that’s powerful enough to “burn” it. Once burnt, the changed dye color records the data. It is through the changes in dye color that digital data is stored in optical discs. The dye used by the disc is vital to data preservation. Unstable dye will fade on its own, which leads to data loss. Being under direct sunlight also deteriorates the dye color in only a matter of weeks or even days.
The sealing of the optical disc is also critical for its data preservation. If the sealing is not of quality, oxygen may enter and react with the chemicals inside, namely the aluminum layer which reflects laser under the dye. Moisture may also enter and cause damage to the chemicals inside.
There was a time when there were many colors for CD-recordables (CD-R’s). There were green, deep blue, light green, black, gold, and other colors. The colors usually differ because of different dye composition. Some manufacturers disguise their dye by adding to the color, but it can be used as a general guideline.
The most common now seems to be light green, which is supposed to be phthalocyanine dye, which is the most stable dye in the CD-R system. It’s the most ideal for archiving in the CD-R world.
DVD-R is one of the two DVD-recordable formats out there. It is not DVD “minus” R, but DVD “dash” R. DVD-R is the first of DVD-recordable formats, and is primarily designed for videos. It is not very ideal for storing data. It does not record a full error correction data into the disc, so if there is damage to the disc, it’s likely that data recovery is either very difficult or simply impossible. The fact that it shares the same types of dyes with DVD+R makes it less of a player in the data storage arena.
Due to its way of recording data, it naturally reads slower than DVD+R. Its major advantages are the fact that it’s the official format of for video format simply because it was developed by the DVD Forum, and the fact that it’s been on the market for longer, so more machines support it (although not significantly more; most machines now support both formats). In other words, there is no advantage of the DVD-R format for storing data.
The other major DVD-recordable format is DVD plus R. DVD+R is technically superior to DVD-R in almost every way. The way it records data makes its signals strong and easily distinguishable for the optical drive, therefore it can be read at a higher speed. Its records full error correction data so that files can be read properly or restored properly if the disc is not-too-severely damaged.
Although DVD+R has technical superiority over DVD-R for data storage, it suffers from one major problem: dye. Turns out, the best DVD-recordables do not have longer storage life than the best CD-R’s in a French study (DEGRADATION NATURELLE D’UNE COLLECTION DE DVD±R GRAVES ENTRE 2004 ET 2008). They are very similar in their storage life. All DVD-recordables are sensitive to light and will deteriorate in a matter of weeks or even days under direct sunlight.
There are mainly two types of Blu-ray Disc Recordables (BD-R). One is HTL, or high-to-low, and the other is LTH, or low-to-high. They are of the same format, just with different types of dye. The terms are named after their physical properties. HTL discs shows lower reflection ratio after they’re burnt, thus high-to-low reflection. Similarly, LTH discs show higher reflection ratio in the burnt areas, thus low-to-high reflection. The recording side of LTH is usually gold in color.
The advantage of LTH is on the manufacturer’s side and not so much for consumers. LTH allows the manufacturer to use the same machines they use to produce DVD-recordables to produce BD-R’s. Whereas this is impossible for HTL discs, and will require the manufacturer to invest in new machines.
Performance wise, LTH is almost inferior in every way. It is more sensitive to the environment, and much less compatible with optical drivers/burners. The French study “QUALITE DES DISQUES BLU-RAY ENREGISTRABLES POUR L’ARCHIVAGE DES DONNEES NUMERIQUES” shows that LTH is obvious inferior when facing temperature and moisture. LTH is also inferior in terms of sensitivity to sunlight. Although LTH is much less sensitive to sunlight than DVD’s, which means sunlight is less likely to cause data loss, but it still performs worse than HTL. The two brands of of LTH discs used in the French study are Verbatim and JVC. Verbatim performed almost equally as well as HTL, although still slightly worse, and JVC was obviously inferior standing against sunlight. The reason for such inferiority to HTL is because the dye is organic, which usually means less chemical stability.
Not to say, LTH isn’t exactly cheap, either. There aren’t many brands using LTH. It has no advantage for data storage over HTL. In fact, there is no obvious advantage for the consumers at all, except perhaps for its attractive gold color on its recording surface.
BD-R HTL – the Best Option
When it comes to BD-R’s, HTL rules. As explained previously, HTL means high-to-low reflection, indicating physical properties before and after burning. The dye is metallic inorganic dye, so it is comparatively more stable than organic dye found in CD-R, DVD±R, and BD-R LTH. Quality matters, however. No matter how reliable the format, if the product is made poorly, don’t expect it to last longer than supposedly inferior formats. By all means, please avoid BD-R’s with the ID prefix of “PRODISC”, they’re absolutely terrible. Unsurprisingly, the manufacturer has pulled out of the optical disc business.
BD-R HTL is literally insensitive to sunlight. The French study “QUALITE DES DISQUES BLU-RAY ENREGISTRABLES POUR L’ARCHIVAGE DES DONNEES NUMERIQUES” has already demonstrated HTL’s resistance against sunlight. Under accelerated ageing tests of 80 degrees Celsius with 80% humidity for 2000 hours, Panasonic and Sony BD-R survived the test, however, Sony was on the verge of death. Panasonic passed with flying marks, as if it could take the same test once more and keep on going.
Panasonic is also the first BD-R manufacturer to be certified by TUV Rheinland to be a media that can last up to 50 years. CMC Magnetics is not included in the French test, but their highest quality BD-R is also certified by TUV Rheinland to be able to last up to 70 years. Whileas Panasonic only releases the best quality BD-R’s on the market, CMC Magnetics releases BD-R of different qualities. I personally believe that their certified discs are of the highest quality in their product line. In other words, if you want archival quality from CMC, purchase their top-of-the-line products. Don’t shy off just because it’s a CMC brand (for those of you who are better acquainted with optical disc brands). In a non-professional but fair test, a person put DVD’s of different brands on the roof for weathering. CMC outlasted even the mighty Taiyo Yuden brand (the best maker of CD and DVD). High-quality CMC discs are definitely worthy of consideration. CMC discs also have higher drive compatibility than, say, Prodisc. I’ve not had problems with compatibility using CMC discs on either Pioneer, LG, or Lite-On drives. I personally purchase only the cheapest BD-R’s from CMC, and I find them mostly okay. I’ve only come across with one set of slightly faulty BD-R’s that work with Pioneer burners but don’t work with Lite-On burners, and I purchased about 450 CMC BD-R’s.
In other words, good-quality BD-R is currently the most reliable and best long-term option for storing data. There are few components to go wrong with an optical disc, and optical discs are more resistant to environmental corrosion. A great feature of optical discs is that data is stored independently of the drive. It can be read almost innumerable number of times, and drives are more likely to wear out before a disc wears out from reading. If a drive is damaged or dies, the disc does not die, the data is safely retained, and replacing the drive will solve the problem. BD-R is much longer-lasting than any other storage medium, is a great leap of improvement over CD and DVD not only in terms of superior dye stability, but also advancement in error correction so it can recover data better. BD-R’s are not too expensive, either. Surely, the advancement of HDD storage has become cheaper per megabyte compared to optical discs (optical discs were cheaper per megabyte in the past), but HDD’s do not last as long, and some HDD’s die more quickly than others.
Besides, BD-R’s are more resistant to weathering. Natural disasters like hurricane, tsunami, etc. have already proven to enterprises and government agencies that only data stored in optical discs survive such disaster. All data stored elsewhere were completely lost. This is why BD-R is making a comeback as an solution for data storage center.
Are optical discs obsolete? If high quality BD-R is considered, no, there is not one storage medium that compares to the lifespan, durability, and reliability of Blu-ray recordables. My personal recommendation for Blu-ray burners / drives would firstly be Pioneer (shown to be of the best brand in the French study), then Lite-On for their versatility (sadly, Blu-ray drives are out of production), and thirdly LG for their second place in burn quality but lower versatility. My personal recommendation for BD-R’s would firstly be Panasonic BD-R (all of their marketed BD-R’s are of archival quality at minimum), which is the best in the world, and secondly Sony, which is the only other brand to have survived the French test, and thirdly CMC Magnetics, which seems to be the best balance between reliability and economy.Written on March 31, 2017 at 3:59 pm