Samsung 840 White Paper page 30

09
Why Integration Matters
What Samsung's Vertical Integration Means to You
The three most crucial components of any SSD are the NAND flash memory, the controller, and the firmware. The
first does the critical task of storing your precious data; the second two work together to accomplish the complex and
equally essential tasks of managing data storage and maintaining the performance and lifespan of the SSD. Using the
control program contained in the drive firmware, the controller (an embedded microchip) executes automated signal
processing, wear-leveling, Error Correcting Code (ECC), bad block management, and garbage collection algorithms,
communicates with the host device (e.g. a PC), and facilitates data encryption, among other tasks. Redundantly stored
in NAND flash, the firmware may be updated manually to improve or extend functionality when the SSD manufacturer
releases an update.
The NAND flash itself is a kind of digital repository, while the controller functions as the command center for
everything the SSD does – from actually reading and writing data to executing the Garbage Collection and wear-
leveling algorithms that keep the drive clean and speedy. Thus, the firmware, which drives the controller, is arguably
the most important component of a good SSD because it delivers the largest difference among branded SSDs in terms
of performance, reliability, and endurance (lifespan). Developing good firmware requires precise engineering skills and
painstaking integration among the NAND flash, controller, DRAM and other SSD components. Intimate knowledge of
NAND characteristics, semiconductor process technologies, and controller characteristics must go hand-in-hand.
Samsung represents one of the few manufacturers that designs all of these components in-house; and, among those
who do, Samsung enjoys the most experience (with over 6 years as the number one supplier in the preinstalled SSD
market).
In-House, Proprietary Firmware
Driving the controller and pulling everything together is the SSD's firmware. The more control a vendor has over the
firmware, the more precise and effective the total package. Samsung is not obligated to use off-the-shelf firmware like
many of its competitors, allowing it to design its own unique performance profile and execute more robust reliability
and bug testing. In fact, customers may notice that Samsung releases very few firmware updates. This is a testament
to the quality of the original testing procedures and the superiority of the firmware code – fewer problems to fix is a
good thing.
In the rare case that Samsung does issue a firmware update, SSD Magician makes it easy to upgrade your SSD.
Magician will notify you of any available updates, and most updates can be completed right within the software itself.
When a DOS-based firmware update is required, the Magician software will walk you through the creation of a bootable
USB drive or CD/DVD, eliminating much of the confusion surrounding the process.
Stability and upgradeability are only part of the story, however. Being the sole steward of its firmware means Samsung
can draft customized garbage collection and wear-leveling algorithms, which have a direct effect on SSD endurance
(or lifetime). Because of some of the underlying design limitations of NAND memory, a write to an SSD is not as simple
as placing data in a storage location. Rather, the SSD is constantly monitoring the use of each individual cell, ensuring
that each one is written to an even number of times to prevent uneven wear and, consequently, premature drive
failure. This process is called "wear-leveling." In tandem, because SSDs cannot overwrite old data without first erasing
it, the controller is also preemptively preparing "free blocks" of space to save time when a write request arrives, a
process that also requires the moving and re-writing of data. Thus, the SSD is constantly moving around data and a
simple write procedure is not a "one-to-one" operation. Since each cell can only endure a certain number of read/
write cycles, the efficiency and effectiveness of the wear-leveling and garbage collection algorithms directly affect the
endurance of the drive. There is no room to waste precious read/write cycles with unnecessary reads or writes – the
more efficient the maintenance algorithms, the longer the SSD will last. Only a company like Samsung, with complete
control of both the NAND and the controller/firmware combination, can squeeze out every last bit of efficiency to
maximize both SSD performance and endurance.
If you are interested in learning more about the jobs SSD maintenance algorithms are responsible for, please refer to
the separate "SSD Maintenance" paper.