The document summarizes the key components and characteristics of solid state drives (SSDs). It discusses that SSDs store data in semiconductor flash memory rather than using spinning disks, as in traditional hard disk drives (HDDs). The main components of an SSD are its controller, which manages the flash memory and interface, and its NAND flash memory. SSDs use NAND flash memory, which can store multiple bits per cell. SSDs have advantages over HDDs like faster access times, greater durability, lower power consumption, and lack of moving parts. However, SSDs also currently have higher cost per gigabyte and limited write cycles compared to HDDs.

1. SEMINAR
Ballarpur Institute Of Technology,
Ballarpur
Department of Computer Science And Engineering
Presented by
Mr. Rohit Dilip Salve
II Year/ III Sem
Session :- 2022-2023

2. ( Solid-state drive )
SSD

3. What is SSD ?
 A Solid-State Drive (SSD) is a solid state storage device that
uses integrated circuit assemblies to store data persistently
typically using flash memory and functioning as seconadary
storage in the hierarchy of computer storage.
 It is sometimes called a semiconductor storage device, a solid
state device or a solid state disk.
 Even though SSDs lack physical spinning disks and movable
read-write heads used in hard disk disks (HDD) and floppy
disks.
 SSD also has rich internal parallelism for data processing.
 SSDs are typically more resistant to physical shock, run silently
and have higher input/output rates and lower latency.
 SSDs store data in semiconductor cells. As of 2019, Cells can
contain between 1 and 4 bits of data.

4. Flash Memory
 There are two types of flash memory NAND and NOR .The names refers to the type of logic gate
used in each memory cell.
 Flash memory (both NOR and NAND types) was invented by Fujio Masuoka while working for
Toshiba
 NAND is a non volatile memory were as NOR is a Volatile memory
 NOR based memory is faster than NAND based memory
 SSD make use of NAND based flash memory to store data.
NAND Storage
 In flash memory each memory cell resembles a standard MOSFET transistor but with an extra gate called floating gate.
 Floating gate help to hold the charge for a long time.

5. Types of NAND
 SSD storage devices vary in their properties according to the number of bits stored in each cells.
1. SLC (“Single Level Cells” with single-bit cells )
2. MLC (“Multi – Level Cells” with 2 bit cells )
3. TLC (“Triple – Level Cells” with 3 bit cells )
4. QLC (“Quad-bit Cells” with 4 bit Cells )

7. • The key components of an SSD are the controller and the memory to store the data.
• Other components play a less significant role in the operation of the SSD and vary among
manufacturers.

8. Every SSD includes a controller that incorporates the electronics that bridge the
NAND memory components to the host computer. The controller is an
embedded processor that executes firmware-level code and is one of the most
important factors of SSD performance. Some of the functions performed by the
controller include:
• Bad block mapping
• Read and write caching
• Encryption
• Crypto-shredding
• Error detection and correction via error-correcting code (ECC) such as BCH
code
• Garbage collection
• Read scrubbing and read disturb management
• Wear leveling
Controller:-

9. Memory
• There are three types of memory in SSDs
• Flash memory based SSDs
• DRAM based
• Other
Flash memory based SSDs
• SSD manufacturers use non-volatile NAND flash memory in the construction of their
SSDs because of the lower cost compared with DRAM and the ability to retain the data
without a constant power supply, ensuring data persistence through sudden power
outages.
• Flash memory SSDs are slower than DRAM solutions.
• Lower priced drives usually use multi-level cell (MLC) flash memory, which is slower
and less reliable than single-level cell (SLC) flash memory.

10. Other
• Some SSDs use MRAM(Magnetoresistive random-access memory).
• Some SSDs use both DRAM and flash memory. When the power goes down, the
SSD copies all the data from its DRAM to flash. When the power comes back up,
the SSD copies all the data from its flash to its DRAM.
• Some drives use a hybrid of spinning disks and flash memory.
DRAM based
SSDs based on volatile memory such as DRAM are characterized by ultrafast data access,
generally less than 10 microseconds, and are used primarily to accelerate applications.
DRAM-based SSDs usually incorporate either an internal battery or an external AC/DC adapter
and backup storage systems to ensure data persistence while no power is being supplied to the
drive from external sources.
If power is lost, the battery provides power while all information is copied from random access
memory (RAM) to back-up storage. When the power is restored, the information is copied back to
the RAM from the back-up storage, and the SSD resumes normal operation.
While the price of DRAM continues to fall, the price of Flash memory falls even faster.

11. Host Interface
• The host interface is not specifically a component of the SSD, but it is a
key part of the drive.
• The interface is usually incorporated into the controller.
• The interface is generally one of the interfaces found in HDDs. They
include:
• Serial attached SCSI - SAS (generally found on servers, >3.0 Gbit/s)
• Serial ATA - SATA (>1.5 Gbit/s)
• PCI Express - (>2.0 Gbit/s)
• Fibre Channel (almost exclusively found on servers, >200 Mbit/s)
• USB - (> 1.5 Mbit/s)
• Parallel ATA (IDE, >26.4 Mbit/s) interface (mostly replaced by SATA).
• (Parallel) SCSI (generally found on servers).

12. Cache or buffer
• A flash-based SSD typically uses a small amount of DRAM as a cache, similar to the
cache in hard disk drives.
Battery or Super Conductor
• Another component in higher performing SSDs is a capacitor or some form of
battery.
• These are necessary to maintain data integrity such that the data in the cache can be
flushed to the drive when power is dropped; some may even hold power long enough
to maintain data in the cache until power is resumed.

13. Attribute SSD HDD
Start-up time Almost instantaneous; no mechanical
components to prepare.
Disk spin-up may take several seconds.
Random access time Typically under 0.1 ms. Ranges from 2.9 to 12 ms.
Read latency time Generally low because the data can be
read directly from any location.
Much higher than SSDs. Read time is
different for every different seek.
Data transfer rate Maximum transfer rate typically ranges
from about 100 MB/s to 600 MB/s,
depending on the disk.
About 140 MB/s in Enterprise HDDs,
depending on rpm which ranges from
4200 to 15000.
Read performance Current SSD technology suffers from a
performance degradation called Write
Amplification
Read time increases if the files are
fragmented.
Fragmentation Its negligible in SSDs If frequently written, HDDs suffer from
fragmentation.
Noise Negligible Relatively more

14. Attribute SSD HDD
Temperature control SSDs do not usually require any special
cooling and can tolerate higher
temperatures than HDDs.
May gain temperature due to moving
parts which shortens the life of HDDs.
Susceptibility to environmental factors No moving parts, very resistant to shock
and vibration.
Susceptible to shock and vibration due to
moving parts.
Installation and mounting Not sensitive to orientation, vibration, or
shock.
Circuitry may be exposed, and must not
contact metal parts. Most recent models
work well in all orientations.
Cost and Storage US$0.59 per GB and are available upto
2TB
US$0.05 per GB and are available upto
4TB as of 2011.
Weight and size Small and light in weight. Heavier and have same form factor as of
SSD.
Reliability and lifetime SSDs have no moving parts to fail
mechanically but have limited no. of write
cycles before it fails.
HDDs have moving parts, and are subject
to potential mechanical failures from the
resulting wear and tear.
Power consumption High performance flash-based SSDs
generally require half to a third of the
power of HDDs.
The lowest-power HDDs use as little as
0.35 watts.2.5-inch drives use 2 to 5
watts. The 3.5-inch drives can use up to
about 20 watts.

15. Disadvantages
The most noticeable disadvantage of SSDs is limited storage capacity compared to
traditional hard drives.
SSDs have high price per GB.
If SSD is damaged it is nearly impossible to recover the data, but HDD's magnetic disk
may be safe even hard drive is damaged.
Till now lifetime of SSD is not so much long.
Some SSDs present in Market
Samsung SSD 840 Pro (512 GB)
• 1 SATA 3.0 interface
• 1 SSD controller (Samsung MDX S4LN021X01-8030)
• 1 RAM module (256 MB DDR2 Samsung K4P4G324EB-FGC2)
• 8 MLC NAND-flash modules, each offering 64 GB of storage (Samsung K9PHGY8U7A-CCK0)
Micron P420m Enterprise PCIe (1.4 TB)
• 8 lanes of a PCI Express 2.0 interface
• 1 SSD controller
• 1 RAM module (DRAM DDR3) 64 MLC NAND-flash modules over 32 channels,
each module offering 32 GB of storage (Micron 31C12NQ314 25nm)
• The total memory is 2048 GB, but only 1.4 TB are available after over-provisioning.

16. Thank You !