Disks with magnetic plates are done for. They are slow, they don’t take abuse well and their repair is half witchcraft, half alchemy – what other computer component can be fixed by baking it in the oven just as well as stashing it in the freezer? We should really get rid of them.
In all possible use scenarios, they are to be superseded by a new technology called solid state drive or SSD, that is much faster, newer, better.
But isn’t that just a marketing ploy to sell a new tech?
Manufacturers of these new disks have been trying to sell SSDs as a storage tech of the future for a while now.
Some of them go a step further and claim that classic hard drives are dead. Violin Memory, for instance, had even actually launched a campaign called ‘Disk is Dead’ and their marketing manager Amy Love stated on the company blog that ‘the all-flash data center is already a reality for many businesses in technology’ and ‘flash storage platforms will be the heart and soul of tomorrow’s datacenter’.
Many people are justly thrilled about SSD and think it actually is the tech of the future. However, marketing campaigns are to be taken with a grain of salt. How is the situation in SSD now? Is it time to dump all the hard drives? Should SSD supersede them in every kind of storage? And will the new technology conquer data centers and servers, as its supporters claim?
Read on and find out.
SSD: No spinning plates, just solid transistors
First a short review. What exactly are these solid state drives, and how do they work? To understand this, it’s necessary to have an idea about ordinary hard drives first.
The hard disk drive or HDD is an engineering marvel. It consists of many very precisely moving parts. The most important ones are the platters that rotate up to 7200 times per minute – and the fastest drives can do up to fifteen thousand revolutions per minute. The platters hold data written in a layer of magnetically soft material. The data is accessed by a moving arm that is holding several heads that read and write bits. The arm glides extremely quickly mere millimetres above the platters and its heads read or write through electromagnetic impulses where necessary. This contraption can very precisely single out a specific spot in the magnetic layer of the disk. It works like an extremely fast record player that doesn’t touch – or indeed scratch – the record at all.
The inner workings of HDD are strikingly similar to a record player. Except that there are no vinyl disks and the read head doesn’t touch them at all. And you usually don’t want to hear any sounds coming from your HDD.
It’s a complex system and as such needs to be treated with care. It can be disrupted just by small shock – like when a notebook falls from a desk down on the floor. Worst case scenario, the read/write heads hit the plates and damage the disk irrevocably. And they are sensitive to heat and other factors, which is an important fact for data centers and servers, as they produce heat in spades.
On the other hand, SSDs are resistant to impact, shocks, vibrations and other factors. And they tolerate heat better than hard drives and produce less of it themselves. It’s all thanks to the fact that SSDs don’t have any moving parts and instead of rotating platters use flash memory based on transistors. The development of SSDs has been heavily influenced by the findings of CPU research, as they are somewhat similar in nature.
Transistors inside the chips of a SSD are assembled into grids made of particular number of rows and columns. At every intersection, two transistors are combined into a cell, where ‘data is stored’ as an electrical current. The input and output part of every cell can decide where the current should flow and consequently, what charge is where. Thanks to this, it’s possible to store the values of one or zero in every cell – in essence, to store information.
Technological processes involved in the workings of SSD are genius, yet somewhat complicated. When choosing the right disk, for instance, you need to be aware of several terms, concepts and acronyms. Like, for example, the acronyms SLC, MLC and TLC. These indicate how many levels one cell of such disk has and how many bits of information it can store. The SLC – single-level cell – drives can store just one bit, whereas MLC and TLC – or multi-level cell and triple-level cell – can store two or three bits of information into each cell. Some companies are now working on new multi-level technology that would allow them to store four bits of information into each cell.
Disks based on SLC can store less data than MLC or TLC disks of the same dimensions. However, singe-level cells and its data can be accessed much faster and will also endure much higher number of rewrites than the other technologies. Those, on the other hand, offer much higher capacity and as a consequence lower price per gigabyte.