What storage medium is best suited for mobile devices
The requirements for storage media in mobile terminals are high: Decisive are capacity, performance, power consumption, noise and life – but also simple.
The requirements for storage media in mobile terminals are high: Decisive are capacity, performance, power consumption, noise and life – but also easy to use.
However, the requirements in the industrial and consumer electronics vary widely and determine the choice of the most appropriate storage medium.
Knowledge is power – even when it comes to selecting a storage medium for mobile devices: Only those who know the peculiarities of alternatives to determine whether they respond to its demands.
Flash memory composed of the memory itself and the controller that controls the write and read operation. The concepts behind like a RAM (Random Access Memory), with the exception of erase cycles: The bytes of flash memory can be addressed individually, but the memory cells only in blocks are deleted. The rewrite would require an erase operation. Their lifespan is max. 100 000. write and erase cycles. Any change in the stored data represents a new writing process and a challenge for the controller: he will have to re-direct the data often to guarantee a certain life. This can cause problems, such as old cells are not transmitted in full or are thereafter only read in part. The margin of error is up to 0.5%. In addition, the performance is limited by the slow writing.
Currently max. 10 Mbit / s are transferred to flash memory – hard drives offer, however fast data transfer rates up to 150 Mbit / s. The loss of time of flash memories reduced their power and manifests itself. In higher access times
First Corollary: Flash memory are used more for reads, hard drives for complex applications.
The two determining flash architectures NAND and NOR flash differ mainly in internal control logic, and thus in the access speed. While NAND large memory provides a small space, can be realized significantly shorter access times with NOR. The market is dominated NAND flash due to the larger memory.
SLC flash memory are virtually no demand in the industry
Further differentiation result from the erase cycles and thus the operational area. SLC chips (see box) address around 100? 000 erase cycles mainly industrial applications such as CNC machines, test systems, database systems or boot drives. This makes them true for industry interesting, but in competition with hard disks and their unlimited erase cycles they can not exist. For complex and time-intensive industrial applications as well as demanding high-end storage operations such as blade servers or highly sensitive industrial plant control disks are also first choice for tomorrow. Therefore, the variant of the SLC flash memory is hardly demanded.
MLC memory with only 10 000 erase cycles again, not suitable for the industry, but even more so for the CE market: Low energy consumption, low operating temperature, very low noise and high shock resistance as well as the small, lightweight design make it an ideal medium for the exchange of data between different devices or as playback media of music, pictures and movies. MLC memory are for example MultiMediaCards (MMC) or USB sticks are used.
In direct competition with flash memories as Fujitsu are external, portable 2.5 “hard drives: The Mobile Drive series is extremely light and a compact, ultra-slim aluminum housing extremely robust. The HDDs are primarily designed for mobile use, without the use of a power supply. Power is supplied via the USB 2.0 interface, a max. Data transfer rate allows up to 60 MBit / s.
In addition, the mobile drive series uses the serial interface technology SATA. Flash memory as the CompactFlash card using the other hand, always a PATA-based interface. Since SATA is almost completely replace the older PATA ports, flash memory can not offer medium suitable connecting interface, and it will lack successors. Internal hard disks, however, can use next PATA and SATA and SCSI / SAS interface technology. In the consumer electronics digital memory chips are in great demand: wherever information persistent – ie not volatile – must be stored in a small space, USB sticks and MP3 players, to memory cards for digital cameras, mobile phones and handheld devices. The small, lightweight design of flash chips is ideal for consumer use. Also, the price-performance ratio is right. Flash memory is a convenient storage – with low capacity requirements. With demand for high storage capacity, the flash cost per Mbyte are however higher than hard drives. Today flash capacities of 128 MB up to 8 GB are common. In comparison, the smallest Fujitsu hard disk stores 40 GB – and costs as much as a flash module with high storage capacity. The break-even point of the hard insert is thus achieved in a demand below 40 GByte. Do not confuse this with SSD drives (Flash Storage vs SSD)
In particular, the mobile hard disk market requires large amounts of memory. The call for more power is growing louder, both for external storage applications as well as in high-end audio / video computing as computer games, video editing, audio recording and DVR. Theoretically, the more memory available, the better graphics, pictures or presentations can be managed. For optimal digital representations and their fast processing, large capacity are therefore inevitable. The capacity limit of Fujitsu’s 2.5-inch HDDs is currently 200 gigabytes. In addition, they offer high shock resistance, quiet operation and low power consumption. These developments enable manufacturers to produce high-end notebooks that rival the performance of corresponding desktop counterparts.
The applications of flash memory and hard drives differ significantly and are rarely in direct competition.
What storage medium is best suited for which application?
This can easily be answered by reference to the advantages and disadvantages of both storage solutions: For applications with low memory requirements and low rate override as MP3 players, digital cameras, handheld etc. Flash technology is ideally suited. For applications with high storage and performance requirements, such as the desktop-use, high-end storage inserts, highly sensitive industrial applications, etc. the hard drive is best suited.
Before flash memory will replace hard drives in mobile devices, tremendous development steps in the Flash technology are needed. So the limited overwriting and the writing speed should be increased tremendously, also enclose the previously announced capacity of 16 GB for a comprehensive desktop use of non – to heranzureichen to the storage capacity of a 200-gigabyte hard drive, a lot of chips would be needed. In addition here would be the price-performance ratio with increasing memory size is no longer competitive.