The most commonly used hardware for data storage now are hard disk drives (HDD) and the more recent Solid-State Drives (SSD). But, there have been a variety of storage mediums throughout history, some were more short lived than others.
Obsolete and near obsolete data storage devices
One of the oldest pieces of data storage technology are punched cards. Punched cards were first used in 1725 by Basile Bouchon and Jean-Baptiste Falcon, the technology was later refined by Joseph Marie Jacquard in his Jacquard loom in 1801. Initially these cards were used to control textile looms; they eventually found greater applications such as their usage in the storage of character codes in the IBM card format, designed in 1928. They are considered an important step in the history of computing hardware.
A commonly used storage device between the 1970s and the early 2000s was the Floppy disk drive (FDD), also known as diskette. The ubiquity of these square plastic encased drives was primarily dictated by their cheap price as well as the high cost of HDDs at the time. Due to the floppy disk’s small storage capacity they were used mainly for the storage of text documents and in some cases pictures. The space limitations made them unideal for larger file storage such as music files. Movie file storage was an impossibility even in the later iterations of floppy disks that had comparatively more storage than their predecessors. Later designs of floppy disks still had less storage capacity than the then new and emerging storage devices such as CD-Roms and USB drives. The space limitation was not a major concern in the early days of floppy disk prevalence as computers were used more as niche workplace instruments.
By the time floppy disks saw their decline computers were increasingly being used for entertainment and media consumption. At that time the low storage capacity of floppy disks became notorious. Floppy disks could not compete with concurrent storage mediums: CD-Roms and USB flash drives. Nowadays you would be hard pressed to find a computer with a floppy disk drive. While everyone over a certain age might be familiar with floppy disks and might have used them atleast once, newer generations are frequently perplexed by these bizarre square devices.
A discussion about obsolete storage mediums cannot be complete without atleast a mention of the infamously unpopular and short lived LaserDisk(LD). LaserDisks looked like today’s CDs and DVDs but were about three times the size. They were used primarily as a storage medium for video and movies and were released at a time when video cassettes led the video storage market. LaserDisks were an improvement over video cassettes in almost every regard. They stored greater quality video and were not ailed with some of the hardware problems cassettes and cassette players had. However, what made LaserDisks so unpopular was the large price tag on LaserDisk players. They simply were not affordable by a large proportion of the consumer base. LaserDisks were released in 1978 and by 1998 only 2% of US households owned LaserDisk players. Still, LaserDisks were instrumental in laying the groundwork for its successors, CDs and DVDs.
While CDs and DVDs are still very popular storage mediums today, they are increasingly being outmoded by the smaller USB storage devices which also have greater storage capacity. In the past CDs were required to play your personal music in automobiles, but newer vehicles have been forgoing CD players in favor of music players utilizing Bluetooth connectivity to access music files. File compression software is more accessible and effective than ever before making it easy for users to store large amounts of video data in their USB storage devices; this reduces the necessity for DVDs.
Hard Disk Drives(HDD)
Hard disk drives are one of the two most popular internal data storage devices nowadays. HDDs were introduced by IBM in 1956 and swiftly grew in popularity to become the dominant form of secondary storage in the early 1960s. The data in an HDD is stored on a spinning disk (or platter). The disk itself is made of a non-magnetic material, but is coated in a shallow layer of magnetic material. A read/write head stores binary information on the disk by magnetizing this shallow film of magnetic material. Data is read from the disk by detecting the transitions in magnetization.
A spindle motor in the disk controls the speed of an HDD’s disk rotation. The rate at which the disk spins varies based on manufacturer specifications. The disks in the first HDDs spun at 1200 revolutions per minute(rpm). Subsequent designs were able to increase the rpm until 3,600 rpm was the average for a long time. Current consumer grade HDDs run at 7200 rpms on average. The greater the rotational speed of the disk the greater the harddrive’s performance will be.
An HDD’s performance or time to access data is determined by two main factors: Seek time and rotational latency. These factors cause delays in the acquisition of data. Seek time is the time it takes for the read/write head to travel to the particular track of the disk that contains the data being received. Rotational latency is caused when the disk sector is not directly under the head when the data request is made.
Seek time is determined primarily by the speed at which the read/write head moves which in turn is determined by the actuator motor. The first HDD had a seek time of about 600ms due to its primitive motor. Since then the seek time has been lowered substantially to about 20ms on average thanks to the invention of the stepper motor and later the voice coil type actuation.
Rotational latency is lowered by having the HDD’s disks spin at a higher rpm. A 7200 rpm disk has an average rotational latency of 4.16ms. Higher grade server harddrives have much higher rpms. 10,000 rpm harddrives have an average latency of 3ms, while 15,000 rpm harddrives have an average latency of 2ms. Note however, with higher rpms comes the drawbacks of higher power draw, higher heat generation and greater noise generation.
A HDD’s storage capacity reported on the operating system is almost always smaller than the drive capacity stated by the system manufacturer when purchased. This is because the HDD automatically allocates a certain amount of space that serves a number of tasks. This space is unusable by the user. The usable space houses crucial operating system files and it might store the drive’s automatic defect management system. Some operating systems also create hidden drive partitions that might be used for system recovery.
HDD storage capacity has improved by leaps and bounds over the years. It has been determined that the storage capacity per square inch of disk surface saw an improvement of 60% per year during 1988–1996, 100% during 1996–2003 and 30% during 2003–2010. The capacity gains for the years 2011–2014 has slowed to 10% per year. Along with capacity increases HDD prices per byte of data have become cheaper over the years: ‒40% per year during 1988–1996, ‒51% per year during 1996–2003, and ‒34% per year during 2003–2010. The price improvement decelerated to ‒13% per year during 2011–2014, as capacity increase slowed.
The first HDD developed by IBM utilized a stack of fifty 24-inch platters and was about the size of two large refrigerators. The size of HDDs continued to get smaller over the years. IMB’s 1962 revision to HDD design lowered the size to about the size of a washing machine, and this was the standard HDD form factor for a long time.
The floppy-disk drive’s prevalence in the then microcomputers is what led to the development of small HDD form factors we see today. People wanted to fit HDDs in their computers in the same way they fit floppy-disk drives. Thus, HDD form factors eventually mimicked the form factors of floppy-disk drives over the ages, first 8-inch, then 5.25-inch, and then 3.5-inch. As laptops and mobile devices began reaching consumer market, even smaller HDDs became available, 2.5-inch, 1.8-inch, 1-inch and 0.8-inch.
Data connection types
The oldest HDDs used a SCSI connection (Small Computer System Interface). This form of data connection had the slowest transfer rate and was used upto the mid 1990’s before they were replaced by the faster IDE connection, otherwise known as parallel ATA connection. Consumer computers used IDE type harddrive data connections for a long time until they were replaced by SATA connections (Serial ATA). SATA type data connection is currently the most prevalent connection used by consumer grade computers. Further technologies have been developed since, SAS (Serial Attached SCSI) is faster than SATA. An advantage of SAS is that the connection cable utilizes the same form factor as SATA and is therefore compatible with SATA slots. Higher end non-mainstream-consumer based hardware can use fiber optic cables for the best data transfer rates. USB connectors are used only for external harddrives as the data transfer rate is not as fast as with SATA.
HDD failure and risks
The read/write head of a HDD, which magnetizes the drive’s disk to save data, travels very close to the surface of the disk, but never touches it. If the head ever touches the fast spinning disk this results in what is known as a head crash. A head crash failure scrapes away the disk’s magnetic film and causes irreparable data loss. Head crashes are most often caused by a sudden severe jolt to the disk such as dropping a harddrive or a laptop while the harddrive is running.
Another issue that might cause head crashes is if the air density inside the harddrive enclosure is too low. If the air density is too low, the head cannot glide over the disk at the appropriate distance. There is a small breather hole in harddrives that connects the internal air of the harddrive to the outside environment. The breather hole has a filter inside called the breather filter. The breather hole is always labelled with cautionary instructions not to cover it. At high altitudes with thinner air special pressurized harddrives must be used in order to preserve proper function.
Humid conditions may also be a risk factor for harddrives failing. If harddrives are kept in extremely humid conditions for long periods of time, the read/write head and the disk might become susceptible to corrosion.
Solid-State Drive (SSD)
Solid-state drives or SSDs are unlike HDDs in that they do not have any moving disks or heads. Instead of using a disk for data storage, SSDs use integrated circuit assemblies for data storage. Since there are no moving parts, SSDs have a much lower probability of failure over time. On top of this SSDs have access times that are much faster than that of HDDs. The only reason HDDs are still competitive currently is because SSD storage is much more expensive. Eventhough SSD prices have been falling rapidly, the price per unit of storage capacity on an SSD is still approximately six to seven times higher than in HDDs; Because of this high cost for capacity, a lot of consumers choose to use low capacity SSDs for the storage of their operating system and other important applications and use a larger capacity HDD for the storage of large user files such as music, videos and pictures.
SSDs initially used DRAM volatile memory, but has since been replaced by NAND non-volatile memory (as of 2009). Sometimes NAND memory is used along with the spanning platter and head of a hard disk drive in order to produce what is called a Solid-state hybrid drive (SSHD). These drives attempt to counter the major deficiency of SSDs, which is their high cost per capacity of data storage, by using the platter to store data. Frequently accessed data is stored as a cache in the NAND memory in order to improve performance, thereby countering the downside of HDDs, which is their slower access time.
Random Access Memory (RAM)
Unlike SSDs, HDDs and the other forms of storage discussed so far, random access memory (RAM) is a volatile memory storage medium, that means information stored is lost by design when the power is shut off. While persistent memory in HDDs and SSDs are used to store data that the user wants to keep, RAM is used as a temporary storage and working space for the operating system and applications.
Secure Digital (SD) cards
SD cards are small persistent memory storage devices most commonly used by small devices like cameras, smartphones, handheld consoles and micro-computers. SD cards employ a form of solid-state storage and just like SSDs don’t employ moving parts. Just like HDDs and SSDs the rate of SD card storage capacity and price efficiency has been improving at an exponential rate since its inception. The standard form factor SD cards gave way to smaller versions of the hardware. SD cards were followed by the smaller miniSD cards and then the even smaller microSD cards.
The storage capacity made significant improvements as standard SD cards were replaced by SDHC (High Capacity), and then SDXC (eXtended Capacity). SDHC slots and SDXC slots are backwards compatible so older iterations of the hardware.
Aside from the above mentioned storage devices there is also software based storage that users may use in order to store data. Cloud is simply a server accessed via the internet, as such cloud storage still uses the some storage hardware to store data, the user simply does not see the hardware because it is located elsewhere. Cloud storage is provided by a variety of companies all with different deals and packages. Most companies give a small allotment of free storage space and require payment, either via subscription or on-demand, for additional cloud storage space. Some notable cloud storage providers include Dropbox, MEGA, Google Dive and OneDrive.
There are a variety of storage devices available currently and consumers have access to a greater amount of storage capacity now than any time in the past. As technology is improving and larger amounts of data is being stored in smaller and smaller hardware, the price per bit of data is becoming increasingly cheap. With this comes an inexplicable drawback, the value of your storage device will depreciate at an ever-rapid rate. So when you are buying your next SSD or HDD or External storage device, be educated about the choices that you make. Considering the rapid rate of storage technology development, your device may become much cheaper months or even weeks after you purchase it.