A solid-state drive(SSD)is a data
storage device that uses solid state
memory to store persistent data. It
is flash based storage device and It
uses same I/O interface developed
for hard disk drives.
SSDs do not have any moving
mechanical components, which
distinguishes them from traditional
magnetic disks such as hard disk
In contrast, SSDs
use microchips that retain data in
non-volatile memory chips and
contain no moving parts.
Development & History
The origins of SSDs came from the 1950s using
two similar technologies, magnetic core
memory and card capacitor read-only
store(CCROS) These auxiliary memory units as
they were called at the time, emerged during the
era of vacuum tube computers.
Later, in the 1970s and 1980s, SSDs were
implemented in semiconductor memory for
early supercomputer of IBM, Amdahl and Cry.
In 1995, M-Systems introduced flash-based solid-
state drives. They had the advantage of not
requiring batteries to maintain the data in the
memory (required by the prior volatile memory
systems), but were not as fast as the DRAM-
Flash memory-based SSDs:
Use non volatile NAND flash memory.
Ability to retain the data without a constant
Lower cost compared to DRAM.
Flash memory SSDs are slower than DRAM
Based on volatile memory such as DRAM.
Internal battery or an external AC/DC adapter is
needed to hold the data.
Ultrafast data access.
Primarily to accelerate application.
Higher cost compared to NAND flash memory.
The controller is an embedded processor and executes
firmware level code.
Every SSD includes a controller i.e. an embedded processor
that executes firmware-level code and is one of the most
important factors of SSD performance.
Bad block mapping.
Read scrubbing and read disturb management.
Read and write caching.
Bandwidth and interleave
• Without interleaving
– For read: 25+100 us per page
• 8000 reads/s = 32MB/s
– For write: 200+100 us per page
• 3330 writes/s = 13 MB/s
• With interleaving
– For read
• 10000 reads/s = 40MB/s
– For write
• 5000 writes/s = 20 MB/s
– 25μs from page to data register
– 100μs transfer in the serial line
– Page granularity
– Sequentially with in a block
– Block must be erased before writing
– 200μs from register into flash cells
Technical Comparison of SSD & HDD
Solid-State Drive Hard Disk Drive
Random access time 0.1 ms. Random access time 5-10 ms.
Read latency time very low. Read latency time high.
100MB/s to 500MB/s. 50MB/s to 100MB/s.
High Reliability. Low reliability.
SSDs have no moving parts to fail
HDDs have moving parts and are subject
to sudden failure.
Small and light weight. Relatively large and heavy.
Till now SSDs are available in size up to
Till now HDDs are available up to 4TB .
Power Consumption 2watts 12 watts.18-Apr-14
High performance-Significantly faster than a
Faster seek time-Up to 60x faster than HDD.
Higher reliability-No moving parts.
Lower power-Lesser power consumption, cooler
Silent Operation-Ideal for post production
Light weight-Perfect for portable devices.
Wider Operating Temp.
They are more expansive than traditional hard
They currently offer less storage space then
traditional hard drives.
Slower write speed.
Set Top Boxes
Privately Held, 2006, Gyeonggi-Do, S. Korea
Claims fastest enterprise class SSD
Very close ties to Seoul National University and Samsung
Distribution deal with Imation who is better known for optical
Controller IP from Indilinx, founded by other SNU graduates
NASDAQ: SMOD, 1985, Fremont, CA
61% of 2007’s $828.4 million revenue was generated by HP & Cisco
SMART recently purchased Adtron
Close ties to Francisco Partners, Silverlake, & Samsung
NASDAQ: STEC, 1985, Santa Ana, CA
Zeus IOPS is the highest performing enterprise class SSD
STEC’s differentiator is its in-house controller technology
Margins could be pressured as competitors improve product
Faster Data Access
Less Power Usage
Latest high-end Laptops and Ultrabooks now
comes with SSD
In coming years SSD will replace HDD