Data Storage Through The Ages

The Early Days

Since the 1940’s man has needed to save electronic information

Initially this was stored on Ferrite beads or cores and was the first type of “Permanent Data Storage” in computer processors. These “cores” although only a few millimetres across were large enough to be wired by hand making an early 4KB core memory a sizeable multi-board item. This non volatile storage was used until the 1970’s as a reliable way to store and manipulate data and could obviously be removed from the computer and transported still retaining the information. A medium sized computer system would typically have 16KB of core memory running bespoke machine code which was very efficient.

Before the arrival of fixed and removable disc drives, Drum storage was popular and was the forerunner to high capacity internal hard discs. Drum storage was like a rotating pile of disc platters with the oxide layer vertically around the smooth outside surface, read and written by adjacent fixed heads arranged in a helical pattern.

To facilitate the loading of software and data onto these systems, paper tape and edge punch cards were created using peripherals called paper tape punches and card punches. Holes were punched in a reel of tape or cards and depending on where the holes were punched the computer could interpret these holes (when read at speed through a reader) as information to carry out a task. The main issue with paper tape was its fragility, although it could easily be disposed of in an emergency and could be repaired with special Mylar patches.

The First Tape

The first major data storage breakthrough came in the early 1950’s with the widespread adoption of half-inch tape coated in Oxide. These tapes were wound on a 7, 8.5 or 10.5 inch open reels and were 300/600/1,200/2,400/3,600 or 4,800 feet in length. The open reel tape heads used were 7-track, 8-track or 9-track, it was the 9-track that finally became the de-facto standard as these were adopted by IBM. Many of the early open reel tape drives were vacuum column controlled and had sophisticated tension and spring arms to take up the slack tape when it was running at full speed and had a BOT (Beginning of Tape) and EOT (End of Tape) marker.

The amount of data that could be stored on tape was anything from 2MB – 220MB using a 6250bpi GCR machine. The tape densities were 200/556/800/1600/3200/6250 bpi, although the most common were 800/1600.

Open reel tape was able to store a far larger amount of data than was previously possible. The half-inch tapes persisted right up until the mid 80’s when they were replaced with cartridge tapes.

Fast forward to today and the modern cartridge tape technology that won out is LTO tape (Linear Tape Open) originally developed by IBM, HP and Seagate (latterly Quantum who purchased the rights from Seagate). The highest capacity LTO tape in use is LTO-5 and this holds a tape that is 846m long, 12.65mm wide and writes 16 tracks per pass and needs 80 passes to write a full tape making 1,280 tracks. An LTO-5 tape holds 1.5TB native with a transfer rate of 140MB/s. The roadmap for LTO tape goes through to LTO-8 storing 12.8TB’s.

The Mainstay Of Today's Storage

The next major Data Storage technology to emerge was the disk drive originally invented in the 1950’s by IBM. These first disk drives were the size of washing machines often with removable multi-platter disc cartridges and they persisted until the 1980’s. In 1979 two brilliant engineers Al Shugart and Finis Conner started Seagate Technology and developed the first 5.25” 5MB disk drive emulating the form factor of the famous Shugart “mini floppy” with a FDD (floppy disk drive) MFM interface. This became a de-facto standard of a 5.25” full height drive the major customer being IBM who fitted these drives in volume to their IBM PC guaranteeing the success of Seagate. Over time the disk drive has become smaller 5.25” half height, 3.5”, 2.5”, 1” and sub 1”, whilst disk capacities have gone through the roof, in 2011 a 3.5” 4TB disk drive will be launched increasing the amount of data storage available to store information to unimaginable levels. The most common storage interfaces available today are SATA and SAS with a spin speed from 7,200 – 15,000 rpm.

The average access time of a 15,000 rpm disk drive is about 4ms and 7,200 rpm disk drive 8.5ms. Whilst spin speeds are unlikely to increase the disk drive capacities are more likely to increase with higher density disk platters and lower profile drives with hybrid SSD (solid state disk) storage providing lightening access times and I/O cache improvements.

Optical For Permanence

Other data storage technologies that are available are based on optical storage, these are CD’s storing 650-700MB, DVD’s storing 4.7GB on a single side or 9.4GB using double sided media, UDO (Ultra Density Optical) storing 30GB on a single side or 60GB on double sided media and finally Blu-ray storing 25/50 or 100GB on a single side. These types of data storage technologies are primarily used to store information for long term 50+ years and include medical, legal, architectural and historical records.

The very first optical storage was developed by Philips in the early 70’s as a “write once read many” (WORM) media, and in the 80’s magneto optical became popular with devices able to store 600MB/1.3/2.6 & 5.2GB capacities. Magneto optical discs started as 12” moving to 5.25” form factor, encased in a plastic sleeve with a ferromagnetic material that used a Red laser to heat the material up to the Curie point in a single spot. This allowed an electromagnetic head positioned on the opposite side of the disc to change the local magnetic polarization, once heated the polarization changes and stored data is retained when temperature drops.

The latest Blu-ray technology also uses a Phase Change technology the same as magneto optical storage. Phase Change material becomes amorphous after high-power laser heating during recording followed by quick cooling and crystallizes with middle-power heating when being erased. The latest BD-XL discs can hold 100GB or 128GB on a single side.

Holographic Storage The Future

Another type of optical storage was holographic and this was being developed by a company called InPhase Technologies but unfortunately it ran out of money before they could make the technology financially viable for mass market consumption. GE is developing a 500GB Holographic storage technology that might see the light of day over the next 2-3 years.

The Fastest Access

Solid state disks (SSDs) are increasingly being used at the very top of the storage tier providing super fast access to data that is up to 100x faster than using a hard disk but are about 25x more expensive. Most SSD storage devices use SLC (single level cell) or less expensive MLC (multi level cell). The primary difference between them is as follows:

1. SLC has a write cycle of 100,000, whereas MLC has 10,000
2. SLC can operate over a greater temperature range and is classed for industrial use
3. SLC uses less power
4. SLC is faster
5. MLC can store more information
6. MLC is more affordable
7. MLC is more prone to unrecoverable errors

The major hurdle with SSD technology is their limited working lifespan in relation to hard disks and the significant cost differences between spinning and non spinning discs. In the real world SSD should only be used an I/O data buffer cache.

The Four Pillars Of Storage

As I sit here and write this in 2011 the world of data storage has moved on a huge amount in the last 70 years. Today we have four storage technologies that are well established and understood.

1. Hard Disks – Currently at 3TB moving to 4TB in late 2011
2. Tape – LTO-5 native capacity of 1.5TB with LTO-6 on the roadmap taking the capacity to 3TB. Tape still enjoys the lowest cost per GB of any other data storage technology.
3. Optical – Always seems to be playing catch-up, the perfect choice for archiving information with the promise of holographic storage to start a new chapter in optical storage.
4. SSD – The most expensive form of data storage and the highest performance. The hybrid technologies of spinning and non-spinning will pave the way we store information for many years to come.

Data Storage Growth

Our world today relies on Data Storage if we make a phone call the information is logged, send an email or text, everything we do with internet / wirelessly connected systems store our data. When we take a photo our images are kept on a SD card ready to be uploaded to our PC, Flickr or Facebook pages, visit the shops and pay by credit card for goods our buying patterns are analysed and offers sent through the post, targeting our tastes. Walk down the street or in a shop CCTV is monitoring our movements and storing footage.

The data we create today is growing at a faster pace than at any time in history, whether we like it or not information is being stored about us and our movements. Recent high profile cases of people posting their Facebook status as on holiday has lead to an increase in robberies. Who has access to this data is also a concern for many with hacked companies making the news daily with the stealing of financial and personal data.

When was the last time you sat down and wrote a letter using a pen and paper? Our daily reliance on data storage is a given. Today we all have a digital camera; it’s either part of the phone or a separate item. We take pictures and videos of family, friends, interesting items and anything that catches our eye. We first upload this data to our PC where we tag, edit and store the captured moment. Most people with a PC or notebook store their data on a single disk drive. The problem with this approach is disk drives fail fact! Why not invest in a NAS system which has two drives mirrored, if one fails the data is still intact http://data-storage.co.uk/index.php/vendors/qnap-systems.

We specialise in providing data storage solutions from the very small to incredibly large storing 100’s of Terabytes of information. Where we store this data is why we started this business. Our knowledge is about providing the right kind of storage for each customer’s unique requirements. If we believe something is wrong we will tell you, conversely we will also assist you if you are going down the right path. I thought many years ago Data Storage was going to get easier to understand and manage it isn’t. The reason is humans are constantly developing new ways to increase performance, store more, compress more, invent new protocols etc.

One of our industry colleagues was excited about a new product they were launching that could cluster Network Attached Storage together; he thought it would change the world of storage at the press of a button. I didn’t have the heart to tell him 20 other companies already make the product and have been successfully for the last 5+ years.

Many times buying data storage equipment is not a race to be first past the post, but whether the equipment will last and provide the storage requirements we need. People are seduced in to buying the latest technology because they got a great deal or was it just a case of being a pioneer, why people buy data storage is a very emotive story. We typically get involved when the “pioneer” has left and the replacement person is trying to understand why he purchased such a technology.

Summary

We cannot claim to understand everything about the data storage technologies available today, but we have a pretty good idea what works and what doesn’t. So if you are interested in talking about a data storage solution then why not give us a call or contact us via email, you never know it might even save you money.