Tape Drives & Embedded Multimedia Cards

Two very different types of storage device – Tape drives and eMMC

You’ll have to excuse the linking of these two subjects into one post.  Although very different entities, I’m not planning to cover either of these in too much detail and felt it was probably more time efficient to combine them into a single post and finishing off my look at storage devices by tidying up loose ends.

Tape Drives
You might be forgiven in thinking that tape drives have little to no part to play in present day computer systems.  For the average home computer user and small business, you would largely be correct in that thinking as, in many respects, tape drives are far less efficient in accessing data than practically any other form of data storage.  Therefore they are of limited interest to most computer users.

However, that being said, tape drives very much have their place in today’s technology and are quite often used to store vast quantities of backup, archived data in large data centres.  This data is almost always held offline, inaccessible to networks or the internet.

Tape drives can be internal or external and internal drives normally hold the common 5.25 inch form factor, just as their optical drive counterparts. Tape drives store data magnetically on a tape that’s enclosed inside a tape cartridge and any such data has to be read sequentially, making seek times for specific information particularly lengthy.

However, IBM have made relatively recent advances in this form of storage technology that allows for data to be read in a file system format similar to that with which we read data contained on optical disc or flash media. This form of system is known as the Linear Tape File System (LTFS) and it’s purpose is to specify how data is stored on tape and how specialised software can read that data.  LTFS works with an open-standards magnetic tape data storage technology called Linear Tape Open (LTO) in order to achieve this.

Although the data capacity of tape cartridges can vary, high end tapes are currently able to store up to 10 Tb of uncompressed data.  This amount of available storage is why data centres still make use of tapes to backup the vast quantities of data that is generated.

Examples of data storage tapes

In a previous couple of posts on SSDs (part 1 here & part 2 here), we looked at the various types of solid state and flash memory.  One device that stands slightly alone from other flash memory is the eMMC.

eMMC stands for embedded Multimedia Card and, as the name might suggest, it’s connected to system internally rather than externally.

As we know, pretty much all of todays mobile devices, including digital cameras, smart phones and tablets, store at least some of their data on internal flash memory.  In the past, a dedicated controller that was driven by the device’s CPU managed the reading and writing of data to the memory.  As technology evolved and the storage capacity of devices improved significantly, it became both impractical and inefficient for the CPU driven controller to manage these functions from outside the flash memory die.

As the capacity of these storage devices improved and the associated inefficiencies became more obvious, eMMC was developed to become a standardised method for placing the controller into the flash die and thereby improving performance, as well as reliability.  Other benefits of this change was the introduction of high-priority interrupt and secure erase and trim

The eMMC combines the flash memory and the flash memory controller as an integrated device on the same silicon die and the solution consists of at least three components;

  • A MMC (multimedia card) interface
  • Flash memory
  • A flash memory controller

The eMMC is not ordinarily user removable, instead acting as in integral part of the circuit board itself within the device, another significant difference to most MMC that we are familiar with.

Study Reference Disclaimer.

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