Flash drives have dominated the world of storage devices with their faster speed, & better reliability than other storage options. Enterprises nowadays prefer flash memories over traditional Hard Disk Drives (HDDs) because of their enhanced performance.
A major confusion surrounding the differences between flash memories, especially NAND & NOR. In this article, we will compare the two flash memory types NAND & NOR to help you better understand.
NAND vs. NOR Flash Memory
The key difference between NAND vs. NOR flash memory is how they read and arrange data. NOR can execute programs directly from the storage unit using XIP features, similar to Random Access Memory (RAM). In contrast, NAND doesn’t have an XIP feature and requires you to buy computer memory to execute programs effectively.
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Feature
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NAND
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NOR
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Random reads
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Slower
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Faster
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Sequential reads
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Faster
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Slower
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Bit-flipping
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More common
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Less common
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Initial bad blocks
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Up to 2%
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0%
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Bad block development
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Less frequent
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More frequent
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Data Retention
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Lower
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Very high
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Program erase cycles
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100,000
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100,000
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Preferred application
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Code storage and execution
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Data storage
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Memory Cell Connections
NOR flash memory uses individual cells to store data into computer memory boards. So, in case of any corruption in one part of the memory, it does not affect others. In contrast, NAND flash memory is vulnerable to data corruption and other errors. To prevent this, enterprises buy Raid controllers to connect all the NAND in a single array, reducing the probability of data corruption.
Read and Write Speed
NAND flash memory has faster read and write speed as compared to NOR memory. This is because NAND does page-based operations, where it transfers large amounts of data sequentially.
In contrast, NOR has byte-level access, which reads and writes individual bytes, making random access efficient, but reducing the speed. That said, NAND has grown more reliable in dealing with large amounts of data Like Solid State Drives (SSDs). On the other hand, NOR is useful in accessing small data randomly such as ICs in computer motherboards.
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Feature
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NAND
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NOR
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Write speed
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Faster
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Slower
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Erase speed
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Slower (520 microseconds)
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Faster (3.5 microseconds)
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Size and Capacity
NAND flash memory is available at higher capacities than NOR flash memory due to its low power consumption and speed. NAND flash memory typically comes in 256 GB to 2 TB storage capacity & more. Conversely, NOR flash memory typically comes in low sizes, as enterprises use it for small data storage like 4 GB to 8 GB & more. Businesses requiring large storage capacity opt to buy HDDs as they come in a variety of sizes including 18TB & more.
Storage Reliability
NOR flash memory has an upper hand in data storage reliability, because of its simpler cell structure and lower storage density. In contrast, NAND flash storage has a complex cell structure and high storage density which causes data corruption also known as bit-flapping.
Many other factors compromise data storage reliability, here are some listed below:
NAND
- Pre-existing bad memory blocks
- Increased bad block formation over time due to wear and tear
NOR
- Zero bad blocks initially
- Lower bad block formation over time
Power Consumption
The power consumption of NOR and NAND flash memory differs significantly in different phases:
Initial Power-On: NOR flash memory takes higher current initially, because of its small cell structure, while the NAND takes less current initially.
Standby: NOR consumes low current on standby, making it ideal for battery-powered devices. However, NAND consumes high current on standby, because of current leakage or flip-flapping.
Active operations: NOR’s short and frequent reads consume less energy compared to NAND but at the cost of speed.
In contrast, NAND erases and writes efficiently due to its page-based operation. This gives an edge to NAND flash over NOR as it provides lower power consumption per bit of data transferred without compromising speed.
Applications
Microcontrollers, code storage, and execution widely use NOR flash memory, as they can retain the data for more time than NAND flash memory. In contrast, NAND has a large storage density with low power consumption per bit making it suitable for large data storage industries like data centers.
Life
Both NAND and NOR have the same write/erase cycle counts, i.e. 100,000 cycles. However, NAND flash drives erase a smaller area of the memory with each cycle because of its sequential memory. In contrast, NOR flash drives erase individual cells, and large memory areas, making its life span shorter than NAND.
Cost
NAND is more cost-effective than NOR due to its smaller size and high storage density. Also, NAND has a lower cost per bit compared to NOR flash memory, reducing the operational cost. However, many companies buy external hard drives with NAND technology, which may increase the overall cost of NAND flash memories.
Pros and Cons of NAND & NOR Flash Memory
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Pros of NAND
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Cons of NAND
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High storage density
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Lower data retention
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Faster read and writes
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Slower random reads
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Low power consumption per bit
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High standby power
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Pros of NOR
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Cons of NOR
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Fast random reads
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Slower reads and writes
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Low standby power consumption
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High power for sequential read
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High data retention
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Low-density
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NOR vs. NAND Flash Which One to Choose?
If you need high-capacity storage drives to perform bulk reads and writes operations, then NAND flash memory is the best choice. If you are in the entertainment industry with a lot of records, you may buy flash memories for higher-quality storage. However, for enterprises that require random reads or code execution, high data retention, and frequent erase cycles, then NOR storage is the best choice.
In the end, it all depends on your needs, requirements, and budget. To get a more clear view of things it is important to understand the difference between NAND vs. NOR flash. Computing Worlds provides a list of the best NAND and NOR flash memory products from the collection of storage devices for sale:
NAND products:
Frequently Ask Questions:
Which Is More Costly NOR or NAND Flash?
NOR flash is more costly than NAND flash, because of the increasing cost per bit as compared to NAND flash.
Why Are They Called NOR and Nand Flash Architectures?
They are called NOR and NAND Flash architectures, because their names are derived from the logic gates used in each memory cell.
The key difference between NAND and NOR flash memory is how each reads and writes data. NOR flash memory uses byte-level access, designed for faster random access, but on the contrary, NAND uses sequential access to read and write data faster, cheaper, and more effectively.
That’s not all, NOR has one greater advantage than NAND flash, which is its reliability and data retention ability. However, both NAND & NOR flash memory come in various storage options such as NVMe or SAS & more.
To get more information about data storage and their comparisons, stay connected with the Computing Worlds blog.
