In This Article
What is Flash Storage?
Flash storage refers to a long-term or non-volatile storage solution that uses flash memory cells to store data and information.
Technically, a flash storage is an electrically programmable high speed memory that does not have any mechanical parts in it. It typically has a flash controller to control access to the memory.
- Flash storage can store data and information in single cell or multiple level cells depending on its type and design and offers faster access to the data and read and write times.
- Flash storage can handle large sets of complex data more efficiently and uses much less energy or generates less heat in the process. It also allows simplified data management and reduces space and cost as well.
- There are different types of flash storage available such as storage array, all flash array, SSD flash drive, hybrid flash storage, NVMe storage and hard drive storage.
- The flash storage can come in different types of interfaces such as USB, SATA, SAS, M.2 and PCI Express.
- This storage option is expensive and its lifespan may not be as high as a mechanical hard drive due to its limited number of P/E cycles.
Understanding Flash Storage
A flash storage uses flash memory chips to attain high speeds during writing and storing data.
Normally, the memory cells that are used in a flash storage for storing the data in it cannot write data directly.
Typically, before writing any new data, the previously written data should be erased first.
The response time of the flash storage is also pretty fast, often just a couple of microseconds, which reduces latency by a significant margin in comparison to Hard Disk Drives or HDDs that come with moving mechanical discs.
Today, flash storage is easily available and people using it experience low power consumption and it also takes much less physical space as compared to the mechanical disk drives.
The flash storage, which comes in different types right from the average USB sticks to enterprise standard all-flash arrays, uses Integrated Circuit or IC technology.
The different types of flash storage are:
This type of flash storage combines several disk drives. This facilitates data storage based on blocks and separates it from the connection functions and network communication.
This, in turn, provides more storage capacity in comparison to a group of file servers.
This type of storage is also known as disk storage array or simply as disk array and allows organizations to access the same data stored in multiple servers across it most efficiently and quickly.
SSD flash drive
These drives store the data and provide advantages over HDD with low latency as it uses flash memory and no mechanical components.
Most of the SSDs available today are typically flash based, which is why the flash storage is considered to be synonymous with a solid state storage solution.
These flash memory storage solutions come with modern architectures and design which increases the performance but without the limitations that are commonly associated with SSD Storage Area Network or SAN legacy functions.
These systems are easily available and offer ultra-low latency which is why these are most suitable to use in multi-cloud settings and storage protocols like the NVMe for example.
NVMe or Non-Volatile Memory Express is actually an interface protocol.
It is fast and is used to access flash storage over a PCIe or Peripheral Component Interconnect Express bus.
This protocol can handle thousands of requests in parallel on one single connection which not only reduces the overhead between the storage and applications but also improves the performance significantly.
Hybrid flash storage
A hybrid flash storage typically uses a combination of HDDs and SSDs.
This gives a perfect balance to the infrastructure enabling it to handle a wider range of workloads.
While the hard drive stores the large and less used files as a backup, the SSD stores the frequently used files and allows easy and faster access to improve the throughput and reduce latency.
Hard drive storage
There is electro-mechanical hardware in these drives that are used to store digital information.
These cost effective options are good to store large files for a long time.
However, the hard drives are known to have latency issues and are also more prone to physical damage due to excessive wear and tear of the moving components inside them.
With the use of flash media these storage solutions can scale further and make the apps work faster.
Irrespective of the type of flash storage used, these play an important role in the modernization of the infrastructure.
It also helps significantly in transforming the economics of data storage by increasing the usable capacity storage and at the same time by improving the performance of the applications.
It is for this reason flash memory is used so extensively today and more advancement is made in this particular area.
There are few specific trends that are noticed at large.
Users now look forward to using SSDs instead of HDDs for higher output and faster performance, though it is a costlier proposition.
There are several organizations that also use a hybrid solution to get both speedier performance and larger storage space.
Flash storage is also used extensively in consumer devices such as MP3s and smartphones. It offers the benefits of compact size and low power consumption.
It is also used in laptops and notebook computers being more resistant to drops, shocks, and high gravitational acceleration hiccups.
These external factors do not affect its performance and therefore the data stays well protected in it.
And, flash storage is also used as a norm for tablets, digital cameras, and digital camcorders for storing data.
Flash storage is a very useful invention that is most suitable for miniaturized devices due to the development of denser flash and photolithographic shrinks which increases its capability.
Flash storage is also used extensively in the enterprise for enhancing the performance of the I/O-intensive apps such as VDIs or Virtual Desktop Infrastructures and databases.
Also, the fall in prices of flash and its low latency and performance benefits have expanded its use even for general purpose workloads as well as for mission-critical apps.
The different formats of flash storage also make it so useful in different fields.
For example, the NOR flash helps in byte-scale memory addressing which, in turn, offers higher read speeds and true random access.
However, compared with NAND, another flash storage format, the erasable NOR flash is costlier per gigabyte due to the larger size of the individual cells.
However, it also has a much slower write and erase speeds as compared with NAND.
NAND flash, on the other hand, provides higher write speed than NOR flash and lower cost per gigabyte due to the string design of the cells.
This not only saves the die space significantly but at the same time it also reduces the overall size of the chip per gigabyte.
NAND can come in different levels such as:
- SLC or Single Level Cell – This stores a single bit of information in each cell and offers much higher speed especially when it comes to writing speeds. Apart from that, it also offers higher longevity and reduces bit errors.
- MLC or Multi Level Cell – This also includes eMLC or Enterprise MLC and offers larger space for data storage. The cells here are capable of higher levels of states or charges which helps it to store several bits of data in each cell. Overall, the MLCs double the capacity of SLC.
- TLC or Triple Level Cell – This offers a third bit. With additional levels of charges and smarter firmware and flash controllers it offers bit error correction as well.
However, both NOR and NAND flash moves electrons through the dielectric material of the cell wall by using quantum tunneling.
However, this, over time, causes the material to degrade.
The flash storage used in the computers also comes in a wide variety of interfaces. This includes:
- USB or Universal Serial Bus
- SATA or Serial Advanced Technology Attachment
- SAS or Serial Attached SCSI or Small Computer System Interface
- M.2 or M dot Two and
- PCIe or Peripheral Component Interconnect Express.
Out of all these different types of interfaces, SATA is the most commonly used one especially in desktop and notebook computers.
Apart from that, typically, SAS-based storage is also extensively used in enterprise systems.
The PCIe offers highest speeds and with the use of NVMe technology this also reduces latency further and increases Input/output Operations per Second or IOPS.
The power consumption is also reduced significantly due to the reorganization of the I/O stack.
There are specific standards of flash memory and these are quite flourishing but still there are a few products that are by nature entirely proprietary, like the memory cards in a few video game systems.
For example, Samsung offers a Phase-change Random Access Memory or PRAM which combines the features of RAM such as its quick processing speed with the non-volatile properties of flash memory.
This particular aspect gives it an apt nickname – the Perfect RAM.
Typically, a PRAM is 30 times faster in comparison to a traditional flash memory and comes with a lifespan which is 10 times more.
How Does It Work?
The flash storage typically stores the data with the help of a charge on the capacitor.
This charge usually represents a binary digit often referred to as bit.
It does not use any mechanical moving parts. Instead, the flash storage is packed with chips mounted on its surface and attached to the PCB or the Printed Circuit Board.
And, there is a flash controller. While the memory chips store the data, this flash controller controls the access to the space for data storage on the memory unit.
The flash controller comes with a specific design that helps it to perform well.
It has multiple channels that work in tandem with the RAM cache.
This cache helps in enhancing the speed of the system by buffering the data that is going into or from a number of chips.
There is a grid of rows and columns in the flash memory with one cell and this cell has two transistors at every intersection.
There is a very thin oxide layer in between the two transistors to separate them from each other.
One of these transistors performs as a floating gate and the other transistor works as the control gate.
The floating gate is the only link to the word line or row through the control gate.
The cell will have a value of 1 as long as this link stays in its place.
In order to change this value from 1 to 0, the flash storage performs a process called Fowler-Nordheim tunneling.
Tunneling is a process that involves changing the paces of the electrons in the floating gate.
An electrical charge normally ranging between 10 volts and 13 volts is applied from the bit line or column on the floating gate for it which enters the gate and drains to a ground.
This charge makes the transistor of the floating gate behave just like an electron gun.
It excites the electrons which are then pushed through the gate to the other side of the oxide layer and get trapped.
This gives it a negative charge. The negatively charged electrons become the barrier between the floating gate and the control gate.
There is a unique device called the cell sensor that controls the level of charges passing through the floating gate.
If the flow of electrons is more than 50% through the floating gate, which is a threshold, it is valued as 1.
When the flow of electrons drops below that threshold, the value becomes 0.
It again becomes normal, or goes back to 1 when an electric field or a higher voltage is applied on the electrons in the cell.
There is a wiring in the circuit that applies this electric field either to a preset section called a block or to the entire chip to erase that specific area of the chip.
This is where new data will be rewritten.
The working process of the flash memory is much faster in comparison to the conventional EEPROMs.
This is because it erases either the whole chip or a particular block to rewrite on it instead of erasing a single byte at a time.
All these happen inside the flash storage without consuming any power.
This is the significant difference between it and flash RAM, which you find in your car radio.
This means that the data stored or the presets in a flash RAM will be lost if the wires are disconnected or the battery dies.
That is why it pulls a tiny amount of current from the battery, even when you switch off the car radio.
Well, that is not the case with the flash storage because it does not need power to retain the data stored in it.
Removable flash storage also has a different working process in comparison to the hard drives.
For example, in the SmartMedia card, there is an electrode which is connected to the chip of the flash storage with wires.
All these three namely, the electrode, the memory chip and the wires are embedded in a resin with a method called OMTP or Over Molded Thin Package.
This eliminates the need for soldering all the three to hold them together.
This OMTP module is fixed to the base card which creates the actual card.
The electrode carries the data and power to the flash storage chip when you plug in the card into a device.
There is a notch that indicates the amount of power needed by the card.
When you hold it with the electrode facing up, if this notch is on the left side it will need 5 volts.
And, if it is on the right, it will need 3.3 volts only.
These types of flash storage can read and write data on small blocks with 256 byte or 512 byte increments.
This makes flash storage pretty fast and capable enough to offer a more reliable performance.
You can also specify the particular type of data you want to keep in it.
These cards are less rugged and therefore should be handled with care.
However, these solid state storage devices are not easily found today because the newer and smaller Secure Digital cards are in vogue.
Depending on the design and model, these newer cards now can be thicker and use a controller chip along with a smaller circuit board.
These also come with larger storage capacities but their design enhances their working process to offer higher speed and performance level.
The advantages offered by flash storage may be different depending on the use cases.
For Data Centers and Enterprises:
For example, when these storages are used in the data centers and enterprises, it provides unique benefits such as:
- Handling huge amount of data with ease
- Much faster performance of the applications such as SAP, Oracle Database, MS-SQL, and VDI
- Efficient handling of big data analytics such as NoSQL and Hadoop databases
- Faster accessibility to data and
- Secure data storage.
Overall, it enables the businesses to make the best out of the new opportunities and capitalize their enhanced productivity and improved outcome. This eventually enables faster time to market.
The use of flash storage also improves the data economics, once again due to its faster and enhanced performance. In addition to that, it also helps in other aspects to save cost such as:
- Simplified data management
- Saving of time
- Reduction in space
- Low consumption of power and
- Reduced cooling costs.
Perhaps the most important benefit of using flash storage is that it future proofs the infrastructure. This will help in meeting the newer and more varied needs of the businesses.
It specifically helps in increasing the potential of the cloud element over time since it will allow optimized integration which will in turn maximize flexibility.
This helps in future growth and scaling without affecting the business in any ways whatsoever.
Other advantages offered by the flash storage include:
- Higher read and write and data transfer speeds in comparison to any typically hard disc drive
- The drives top in terms of performance but they also are highly durable since these types of storages do not come with any moving parts but perform only on electrochemical procedures
- The small form factor that does not compromise with its capacity but consumes little real estate to be accommodated in the computer
- Higher reliability due to less wear and tear and failures due to the lack of moving mechanical discs inside
- More efficient performance with little requirement of energy for it to perform and
- Silent performance due to the absence of spinning discs inside the storage.
Most importantly, the flash storage devices are highly portable and therefore will allow you to ‘carry your data’ anywhere you want ‘in your pocket.’(All puns intended.)
However, everything about flash storage may not be good for every user. Here are a few downsides that may be a point of worry for different users.
One of the most significant concerns for the users of flash storage, especially the enterprise, is the price.
Though the cost has come down recently, it is still much, much higher in comparison to the conventional hard drive storage solutions.
Limited P/E Cycles
Another significant drawback of the flash storage is its limited PE cycles which are also known as write/erase cycles.
Add to that, its lifespan is also not as long as a mechanical hard drive, depending on the usage.
The flash memory can erase only one block at a time which typically sets all bits in that particular block to 1.
In that case, the flash memory, especially the NOR flash, offers random access programming and read operations but does not offer random access erase or rewrite operations.
The data structures in flash storage usually are not possible to update entirely in general ways and can be removed by labeling them as invalid.
This specific process needs to be modified in the case of multi-level cell devices because here the memory cells store in excess of one bit.
The solitary block level interface or the Flash Translation Layer or FTL offered by the common USB flash storage and memory cards allows writing to a different cell every time in order to wear-level the device.
However, this does not allow incremental writing in a block though it prevents the device from wearing out prematurely due to rigorous write patterns.
Data retention in a flash memory is also another concern due to the continuous de-trapping of the electrons.
Due to this the stored data on the flash cells is lost steadily. This rate of loss increases exponentially with the increase in the absolute temperature.
Another significant limitation of flash storage is memory wear. Typically a flash memory has a limited number of Program/ Erase or P/E cycles.
Usually, this is about 100,000 P/E cycles for any standard flash products available before integrity of the storage starts to deteriorate due to wear.
This feature does not make flash storage very useful for high-reliability data storage that needs to go through a very high number of program cycles.
This is a condition in which the process used to read a memory block in a NAND flash memory causes the neighboring cells to become programmed or change over time within the same memory block.
During a read disturb condition when one particular cell is read continuously it may not fail but the surrounding ones can during a subsequent read.
If the flash controller is not able to intervene in time it will cause read disturb error, which, if numerous, may result in loss of data.
Typically, the Integrated Circuits of the flash storage come in BGA or Ball Grid Array packages.
Those that do not are usually mounted on a Printed Circuit Board beside other BGA packages.
These BGA packages are normally X-rayed to check whether or not the balls and the pad are connected properly or need a rework.
The x-ray however may erase the programmed bits in the flash storage and convert the programmed ‘0’ bits into erased ‘1’ bits.
Usually, flash storage tends to have a drag when reaching higher capacities, such as 1 TB for example, as it is in the case with Hard Disk Drives.
This may result in performance issues eventually.
Finally, flash storage, especially those memory card types, are more vulnerable to physical damages.
These can be broken or lost or may be unreadable due to electronic corruption. Therefore it needs careful handling.
Is Flash Storage Same As SSD?
This needs a fair bit of explanation in order to understand the differences between an SSD and a flash storage in a much better way.
Usually, a non-volatile Solid State Drive or SSD stores data persistently and for that it uses a solid-state flash memory.
The most important parts in it include a flash controller and NAND flash memory chips.
The design of the SSD controller optimizes the read/write performance keeping it high for both sequential as well as random data requests.
The chips are stacked in a grid by the manufacturers in order to achieve varying capacities and densities.
Each flash memory cell in the SSD storage comes with a transistor which is commonly referred to as a FGT or a Floating Gate Transistor.
As said earlier, this floating gate is separated from the control gate by a thin oxide layer.
This regulates the electrical current flowing through the gates.
The FGT prevents volatility and enables the SSDs to preserve the stored data even if these are not connected to a power source.
In an SSD, every FGT holds a single bit of data. If this bit is identified as a 1, it implies that it is a charged cell.
On the other hand, if it is designated as a 0, it means that the cell does not have any electrical charge.
The flash memory works by adding or charging and removing or discharging electrons from the floating gate.
Now, does these all mean flash storage and an SSD are the same? Well, not really.
Even though these two terms are often used interchangeably, they surely have different meanings and come with different features and functionalities.
For example, the SSDs contain flash storage and flash storage is just one component of it.
Usually, all SSDs come with a flash storage but not all flash storage may be used in an SSD.
There are several other applications of a flash storage such as:
- Micro SD or Secure Digital cards
- USB flash drives
- Digital cameras
- Handheld gaming consoles and other mobile devices.
The flash storage may be of two kinds such as NOR and NAND of which NOR is older, larger and less costly. NAND, on the other hand, is smaller in size and has much faster write speeds. This is why it is favored the most for SSDs.
As you may know already, flash storage can come in different form factors but the SSDs typically have fewer varieties in comparison.
And, apart from cost and compatibility, the SSDs have been around for a longer time than the flash storage.
However, there are some similarities between a flash storage and an SSD and one of the most notable similarities in them is that they both do not come with any moving mechanical parts inside them.
And, the data stored in both of them are considered to be non-volatile in nature.
What is a Flash Storage Example?
Here are a few common examples of flash storage and devices where flash memory is used:
- Multi-Media Cards or MMCs to store text, images, audio and video in smartphones, video camcorders, digital cameras, personal computers and music players
- The BIOS or Basic Input/output System chip in a computer motherboard to store instructions for basic functions such as keyboard control or booting
- CompactFlash that is mostly found in digital cameras
- SmartMedia that is also found in digital cameras
- Memory Stick also found in digital cameras
- PCMCIA Type I and Type II memory cards found in the SSDs in laptops and
- Memory cards in gaming consoles.
With the advancement in technology, the use of flash storage is expected to be more extensive in the years to come.
Is Flash Storage The Same As Hard Drive?
In simple words, the flash storage is not the same as the conventional hard drives in the sense that it does not contain any moving mechanical disc inside as an HDD.
The NAND flash storage, in particular, offers a lot of advantages over the traditional HDDs in spite of its higher cost. These are:
- Higher performance
- Lower power consumption
- Reduced latency and more.
And, at an enterprise level, the faster flash storage than HDDs offer significant help in system management, power and cooling costs and system maintenance.
The data footprints of the enterprises are also reduced significantly due to more sophisticated data reduction technologies such as inline compression and de-duplication in all flash storage systems as compared to the HDDs.
However, there are a few caveats associated with flash storage that are often overlooked by most of the users.
The high speed and random read access comes at a high cost and reduced longevity due to heavy use and higher write workloads.
The comparatively limited tolerance of the flash storage than the HDDs for write/erase cycles also affects its endurance.
This issue is however resolved by the manufacturers implementing better features such as DRAM/non-volatile RAM caching or wear leveling to augment the performance of the flash storage.
Also, the lowered flash SSD write wear enhances the reliability quotient of the flash storage.
The flash storage is one of the different types of storage options that are quite popular due to the benefits that they offer to the users.
With higher read and write speeds these are used by several data centers and enterprises.
However, not all SSDs are flash storage, and you know why, thanks to this article.