SSD benefits over HDD

1. TOSHIBA Storage Products for ICT Society 2
Trends in Technologies for HDDs, ODDs, and SSDs, and
Toshiba’s Approach
By HATTORI Masakatsu, SUZUKI Hiroshi, SUGAYA Seiichi
Demand for data storage devices has been exponentially increasing with the widespread dissemination of the
Internet and cloud computing.
In response to this situation, Toshiba has been developing and supplying all of the main types of storage
devices, including hard disk drives (HDDs), optical disc drives (ODDs), and solid-state drives (SSDs) using NAND
flash memories. With the ongoing diversification of storage device market needs ranging from personal use to data
centers, we are making efforts to accelerate several new technical innovations to meet a wide variety of storage
requirements.
Trends in HDDTechnologies
Due to the spread of the Internet and cloud com-
puting, in recent years demand for storage devices has
been increasing. Figure 1 shows the changes in the
volume of data generated worldwide and the capacity
of storage devices for storing such data. It is said that
the volume of data generated worldwide has been
increasing by more than 40% annually, yet hard disk
drives (HDDs) are still the dominant storage devices.
HDDs have been able to remain the dominant
type of storage device because they have maintained
their advantage over the other types through steady
improvements in their recording density for more than
40 years. As shown in Figure 2, which details the his-
tory of improvements in recording density, not only
magnetic heads and magnetic disks but also other
technological innovations in various fields have sup-
ported improvements in recording density.
Technological innovations that have■
supported HDDs
Since 1997, the year in which giant magneto
resistive (GMR) heads appeared, recording density
improved by 100% annually until dropping to 30% in
2001 due to a slowing in the pace of advancement.
The practical application of the perpendicular mag-
Trend
Year
Total
Flash memory other than SSDs
SSD
HDD
Exa: 10
18
1,800
1,600
1,400
1,200
1,000
800
600
400
200
0
Totalstoragecapacity(Exabytes)
2006 2007 2008 2009 2010 2011 2012 2013 2014 2015
Figure 1. Trends in global information creation and storage capacity — Due to the
spread of the Internet and cloud computing, data storage capacity has been increasing
by 40% annually.
Year
10,000
1,000
100
10
1
Arealrecordingdensity(Gb/in
2
)
BPM
Energy-assisted magnetic recording
Shingled Magnetic Recording (SMR)
LDPC channels
Dynamic Flying Height (DFH)
AntiFerromagnetic Coupling (AFC) media
Fluid Dynamic Bearing (FDB) motors
GMR heads
40% per year
Perpendicular magnetic recording
Tunnel Magneto Resistive (TMR) heads
Ramp load mechanisms
PRML channels
1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 2017
30% per year
Growth: 100% per year
50% per year
PRML: Partial Response Maximum Likelihood
Figure 2. Trends in areal density of HDDs and innovation technologies — Recording
density has been improving thanks to technological innovations in various fields,
including magnetic heads and recording media.

2. TOSHIBA Storage Products for ICT Society 3
SPECIAL REPORTS
netic recording method restored the rate of improvement to 50% in 2005.
In this way, technological innovations in magnetic heads and magnetic disks greatly contributed to improvements in
recording density. However, channel technology, error correction technology, servo control technology, and other technolo-
gies have also facilitated improvements. For example, recently released storage devices feature a new error correction
method that uses low density parity check (LDPC) codes. All storage device makers are adopting these codes quickly as
they improve the signal-to-noise ratio (SNR) by 2 dB or more compared with the conventional Reed-Solomon error connec-
tion codes (RS-ECCs) (refer to pp. 10–14).
New technologies to watch■
To further improve recording density in the future, we have been developing Thermal Assisted Magnetic Recording
(TAMR) or also called Heat Assisted Magnetic Recording (HAMR). This technology induces magnetization reversal using
laser-emitted thermal energy to balance the trade-off between ensuring thermal stability and the difficulties in writing to
magnetic disks. In these processes, data is written to a magnetic disk by focusing a laser beam on very small spots in
order to heat only very specific small sections of the disk. TAMR (HAMR) is gaining attention as a technology capable in
theory of achieving a magnetic recording density of 3 T (Tera = 1012
) bit/in2
.
Microwaves are considered to be another supplementary measure and are applied in Microwave Assisted Magnetic
Recording (MAMR) technology. Here, the spin-torque oscillator—an ultra-small microwave generator—is used to send
microwaves to tiny sections of a magnetic disk, eventually lowering the required amount of magnetic energy necessary to
write data. In theory this technology can also achieve a magnetic recording density of 3 Tbit/in2
.
Bit Pattern Media (BPM) technology allows for small bit patterns to be physically processed and has also been studied
as a magnetic disk technology. Toshiba has been developing these future technologies in collaboration with parts suppliers
and its research and development divisions.
In the meantime, Shingled Write Magnetic Recording (SMR) is an approach for improving recording density which dif-
fers from traditional approaches. This technology uses existing perpendicular magnetic recording technology and improves
recording density by altering the algorithm used to record data to magnetic disks. In this approach, data tracks are not sep-
arated when writing data, but a new data track is recorded while layering part of the data track over the previous track.
Since this method of writing data resembles the way shingled roofs are installed, this technology is called as shingled
write recording. In theory, a recording density approximately 1.5 times that achieved by the perpendicular magnetic record-
ing method is possible. Although it depends on the limitations of the perpendicular magnetic recording device, a recording
density of 1.5 to 2 Tbit/in2
can be achieved using this technology.
Servo technology (positioning technology) is also an essential technology supporting improvements in HDD recording
density. The most recent HDDs use a track pitch of 100 nm or less, requiring accurate positioning to the target track at a
pitch of 10 nm or less. In principle, positioning is performed by the feedback control based on the position information writ-
ten to the magnetic disk in advance. To achieve this positioning, we have developed technologies related to vibration charac-
teristics, oscillation measures, dual-stage actuators using Piezoelectric elements, and eccentricity correction, among others.
Information security for the ICT society■
As the scope of applications for HDDs expands, additional functions come to be demanded in addition to those ensur-
ing basic performance such as vibration resistance, shock resistance, and low power consumption. Of such functions,
encryption is one important technology. Especially recently, the use of encryption technologies to protect data written to
HDDs is increasing due to the spread of cloud computing and rising awareness regarding the needs for personal

3. TOSHIBA Storage Products for ICT Society 4
SPECIAL REPORTS
information protection and maintaining confidentiality. We have also been proposing products based on Toshiba’s own pro-
prietary encryption technologies, such as our “Wipe Technology HDD” (refer to pp. 20–23).
Trends in ODDTechnologies
Acceleration and spread of commoditization■
Since DVD drives are now low cost optical disc drives (ODDs), they are regarded as standard equipment in the world
of PCs. Tablets, which generally lack DVD drives, are currently spreading rapidly. In response to this increase in the number
of PCs without DVD drives, demand for external DVD drives is growing. In the audio-visual (AV) market, although Internet
distribution is increasing, DVDs are still the dominant media for distributing content.
A large capacity optical disc, the Blu-ray disc (Note 1)
, has been released as the successor to DVDs. In developed coun-
tries, the Blu-ray disc market has been gradually growing as flat-screen high-definition (HD) digital TVs and HD broadcast-
ing spread. It is estimated that effective Internet
connection speeds will not be able to keep pace
with the explosive increase in Internet usage, which
will eventually drive the spread of Blu-ray discs
(Figure 3).
On the other hand, in emerging countries
undergoing rapid economic growth with huge popu-
lations, it is expected that distributing content by
easy-to-use, less expensive optical discs will estab-
lish itself as a method before advanced Internet
infrastructure is even developed.
DVD drives■
DVD drives for PCs now enjoy sales of 300 mil-
lion units per year and recording devices account for
80% of that total. In addition, in response to the
growth of notebook sales, the percentage of slim
models has been increasing (Figure 4). Still,
demand for low cost ODDs is becoming stronger as
a result of the commoditization of notebooks.
To meet such low cost needs, Toshiba Samsung
Storage Technology Corporation, which is engaged
in the DVD drive business, has developed slim DVD
recording drives with a refreshed design by using
the value engineering (VE) (Note 2)
technique (refer to
pp. 30–33).
(Note 1), (Note 3) Blu-ray Disc™, Blu-ray™, and BDXL™ are trademarks of the Blu-ray Disc Association.
(Note 2) Value Engineering
A technique to achieve the required functionality at minimal cost by analyzing the value of a product or service in terms of the relationship
between function and cost.
Year
60
50
40
30
20
10
0
GlobalIPtraffic
(Exabytes/month)
2009 2010 2011 2012 2013
6
5
4
3
2
1
0
Internetvideobitrate
(Mb/sec.)
Global IP traffic
Bit rate (Japan)
Bit rate (France)
Bit rate (U.S.)
IP: Internent Protocol
* Based on data from “Cisco Visual Networking Index: Forecast and Methodology, 2009–2014”
(1)
Figure 3. Trends in global Internet Protocol (IP) traffic and Internet speed —Internet
speeds in developed countries are not keeping up with the increase in data usage.
Year
Slim Blu-ray disc
Slim DVD recording device
Other slim devices
Half-height Blu-ray disc
Half-height DVD recording device
Other half-height devices
400
350
300
250
200
150
100
50
0
Productionvolume(millionunits)
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
* Based on Techno System Research’s “Long-term forecast for ODD, Data Y10”
(2)
Figure 4. Trends in ODD market (volume by drive type) — 300 million ODDs are produced
annually. Recording devices account for 80%. The production of slim devices has been
increasing.

4. TOSHIBA Storage Products for ICT Society 5
SPECIAL REPORTS
Blu-ray disk drives■
Media for movies and other content is gradually shifting from DVDs to Blu-ray discs as Blu-ray players and recorders
spread. However, the difference compared to DVDs in cost of both Blu-ray disc drives and discs is significant because of
the large difference in the production volume and structure. Such differences have become barriers to the adoption of Blu-
ray technology. Toshiba and Toshiba Samsung Storage Technology Corporation plan to promote Blu-ray by applying the
above-mentioned VE technique also to Blu-ray disc drives and producing key components in-house.
At the same time, in order to provide high-value added products, both companies have been developing technologies
to record high quality data at high speeds to the new standard three- and four-layer recording discs (BDXL™ (Note 3)
) as well
as optical pickups for ultra-slim drives (drive height: 9.5 mm).
Next-generation large capacity optical disc technology and its applications■
Various technologies to realize the next-generation large capacity optical discs which will succeed Blu-ray discs have
been pursued. Research on methods to significantly increase the number of recording layers of discs from the current max-
imum of four as well as other methods for using discs by stacking many thin discs on top of each other has been con-
ducted in order to increase the recording capacity per disc volume based on Blu-ray disc technology.
In the meantime, as methods to increase recording density and capacity by using recording principles different from
the above, other technologies such as hologram recording, which uses the effect of the interference of light, near field
recording, in which data is recorded by reducing light spots, and super high resolution recording have also been studied
(refer to pp. 24–29).
Some think that as HDDs will be used widely for data backup and other purposes by both individuals and enterprises
because of their high capacity, low cost per byte, and high-speed data transfer capabilities, the range of application of
large capacity optical discs will narrow. However, the need to save important data securely for the long term is growing
due to increases in the amount of data handled in the fields of official documents, legislation, and medicine; a strengthen-
ing of regulations; and an increase in the amount of audio and visual data recorded by families for personal use.
In these fields, the advantages of optical discs, including a reduced likelihood of being affected by fluctuations in tem-
perature, humidity, and other environmental factors; portability and ease of use; and resistance to the elements can all be
utilized. To this end, Toshiba has also been researching technologies that can guarantee long-term storage of data as well
as technologies for recording data in high quality.
Since 3D movies and high resolutions such as 4K2K (4,096 × 2,160 pixels) are expected to prevail in the future, next
generation high capacity technologies to realize high capacity content distribution discs will very likely be developed.
Trends in SSDTechnologies
In a computer, the data access speed of the main memory (i.e., DRAM) and that of external storage devices (i.e., HDDs)
differ in performance by 5 or 6 digits. To eliminate bottlenecks in system performance by reducing this difference, the
deployment of Solid State Drives (SSDs), which use NAND flash memory as their recording media, has been increasing.
Storage systems in which many high-speed HDDs are connected in parallel to maintain system performance can sig-
nificantly reduce the number of HDDs required through tiering technology that combines SSD with low-speed large capac-
ity HDDs. SSDs significantly improve space efficiency, power consumption, and Total Cost of Ownership (TCO) (Note 4)
and
are essential system components for achieving green ICT (refer to the boxed article on the next page).
(Note 4) TCO
The entire cost of a complete IT system, including installation, operation, facilities, etc.

5. TOSHIBA Storage Products for ICT Society 6
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Prospects of Storage Devices in the Enterprise Market
In servers and storage systems, storage devices
have traditionally been layered based on the frequency
of information use. As shown in Figure A, the bottle-
neck in access performance can now be eliminated by
installing an SSD in the top tier (Tier-0). In general, it is
considered that 80% or more of data access is concen-
trated on an area accounting for 20% or less of the
entire storage capacity. Storage system companies
have put the automatic tiering technologies for
extracting high access data (alternately, “hot data”)
and reallocating such data on SSDs to practical use.
Using SSDs as data caches is a growing trend,
and SSDs directly connected to a Peripheral
Component Interconnect Express (PCI Express (Note 5)
)
bus, which has superior access latency, would show
promise for the future.
Growth in the enterprise SSD market remains
slow. However, with applied technologies including
automatic tiering becoming available and resolution of
the bottlenecks on the system side that have thus far
hindered SSDs’ intrinsic high-speed performance, it is
expected that SSDs will rapidly be deployed in the
server and storage system markets, which are the
main target markets for enterprise SSDs (Figure B).
In HDDs, in addition to high-speed HDDs for the
enterprise market, nearline HDDs, which enjoy supe-
rior unit price with regard to capacity thanks to tiering
technology, are increasingly used as storage devices
for low-access data in cases where particularly high
performance is not required. Demand for nearline
HDDs is increasing. However, total storage capacity
has been increasing exponentially as stated above,
and the need for low power consumption at data cen-
ters is growing, partly as a result of the adoption of
anti-global warming measures. Although current main-
stream nearline HDDs are 3.5-type models, it is
expected that use of 2.5-type models, which have
superior power saving performance, will increase in
the future.
(Note 5) “PCI Express” is a trademark or registered trademark of PCI-SIG.
System consisting enterprise HDDs only ILM-based tiering Introduction of SSDs
10 krpm
HDD
10 k/15 krpm
HDD
7.2 krpm HDD
Tier-1
Tier-2
Tier-0
Tier-1
Tier-2
SSD
10 k/15 krpm
HDD
7.2 krpm HDD
Dataaccess
frequency
Data access rate (Image)
15 %15 % 80 %80 %
100 %100 %
100 %100 %
Capacity ratio
Access rate
0 20 40 60 80 100
Dataaccess
frequency
Data access rate (Image)
15 %15 % 80 %80 %5 %5 %5 %5 %
Capacity ratio
Access rate
0 20 40 60 80 100
5 %5 %15 %15 % 80 %80 %
50 %50 % 30 %30 % 20 %20 %
Capacity ratio (%) Capacity ratio (%)
Figure A. Tiered Storage — Performance improvements can be achieved by introducing an SSD to Tier-0. By replacing
some of the high speed HDDs with SSDs, space efficiency, power consumption, and power efficiency can be
improved, thereby reducing TCO.
2010 2011 2012 2013 2014
7
6
5
4
3
2
1
0
Year
Volume(millionunits)
Read-intensive and boot SSDs
SATA
SAS
Fiber channel
Low cost PCI Express
PCI Express
SATA:Serial Advanced Technology Attachment
SAS: Serial Attached SCSI (Small Computer System Interface)
Figure B. Trends in the Enterprise SSD Market —
According to a market forecast on interfaces
(Toshiba’s estimate), HDD-compatible SAS and
SATA have the most market share. However,
the percentage of SSDs directly connecting
through PCI Express will increase gradually.
Item HDD Item SSD 10 k/15 krpm HDD 7.2 krpm HDD Total
Number of drives (slots) 334 Number of drives (slots) 25 50 80 155
Power consumption (W) 2,340 Power consumption (W) 163 350 984 1,497
Performance
(Total IOPS or klOPS)
100 Performance
(Total IOPS or klOPS)
1,703 15 13 1,731
Power efficiency (IOPS/W) 42,7 Power efficiency (IOPS/W) 10.4 42.9 13.2 1,156
■ Benefits (1) Number of drives 50% or less → Improved space efficiency
(2) Power consumption Improved by 36% → Reduced TCO
(3) Performance Improvement of 17 times → System bottlenecks eliminated
(4) Power efficiency Improvement of 26 times → Realization of green ICT
ILM: Information Life Management IOPS: Input and Output per Second

6. TOSHIBA Storage Products for ICT Society 7
SPECIAL REPORTS
SSDs and HDDs■
SSDs and HDDs are both major storage devices, each with their respective strengths (Figure 5). Although HDDs are
widely used as storage devices that have good balance with respect to capacity, performance, and reliability, they have
data access speed limitations due to their mechanical structure. By contrast, although the access performance of SSDs
exceeds that of HDDs by a two-digit figure, HDDs are still less expensive in unit price per gigabyte. As demand for data
storage grows in terms of capacity and performance, both drives will coexist by complementing each other.
Characteristics and control technology for SSDs■
SSDs are quite different than HDDs in their write endurance and data retention times. Regarding write endurance,
SSDs adopt wear leveling technique to average write and erase cycles on the NAND cells, a data management technique
to efficiently consolidate fragmented data (garbage collection), and Self-Monitoring, Analysis and Reporting Technology
(S.M.A.R.T) for life management. Regarding data retention time, data integrity is ensured by the SSDs’ patrol functionality,
which is also effective against read disturb (Note 6)
and program disturb (Note 7)
phenomena, which are unique to NAND flash
memory. Further, the data retention time in the power-off state is compliant with JEDEC standards(3)
and can meet system
requirements in normal use cases.
(Note 6) Read disturb
If a page is read many times, other pages in the same block are affected.
(Note 7) Program disturb
When writing a program, cells other than the program’s target cells are affected.
Cost per byte
(GB/$100)
Capacity per power consumption (GB/W)
Random performance per
power consumption
(×10 IOPS/W)
Random write performance
(×100 IOPS) )
Transfer rate (Write)
Transfer rate (Read)
Large capacity
Power consumption/Capacity and /IOPS
Sequential transfer rate
Random read performance
(×100 IOPS)
Random access performance
1,000.0
100.0
10.0
1.0
0.1
(b) Comparison of characteristics
High performance SSD
2.5-inch 15 krpm HDD
3.5-inch 7.2 krpm HDD
Figure 5. Differences in characteristics of SSDs and HDDs —Both SSDs and HDDs have unique characteristics
and advantages derived from their respective structures. HDDs have an advantage in unit cost per byte, and
SSDs have an advantage in data access performance. (This figure shows general differences and does not
compare specific products.)
(a) Pros and Cons
SSD HDD (10 k/48 krpm)
Pros
- High performance 20 k-100 kIOPS
200-500 MB/sec.
Low cost per performance ($/IOPS)
- Fast response, low latency
- No mechanical parts
- Robustness to external vibrations and shocks
- Market-proven HDD technologies
No limitations on write endurance
No limitation on data retention
- Wide variety of products
- Low cost per byte ($/GB)
- Low power consumption per byte (W/GB)
Cons
- New storage technologies
- P/E endurance (P/E limitations)
- Data retention
- High cost per byte ($/GB)
- Performance 200-400 IOPS
150-200 MB/sec.
Seek and rotational latency
- Resistance to external vibrations and shocks
- Long startup times
P/E: Program/Erase

7. TOSHIBA Storage Products for ICT Society 8
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Types of SSD products■
Existing SSD products can be classified into client SSDs, which are mainly used for personal computers and terminal
devices, and enterprise SSDs (refer to pp. 15–19), which are used for servers and storage systems for data centers and
corporate systems (Tables 1 and 2).
Client SSDs●
The main advantages of SSDs include high speed data access, short start-up times, low power consumption, and
improved reliability (vibration and shock resistance). Current mainstream client SSDs are compatible with 1.8- and 2.5-type
HDD sizes. However, more smaller form factors and system-specific implementation are also available in response to the
diversification of client and mobile systems (Figure 6). The flexibility of implementation that HDDs cannot realize is also
one of the advantages of SSDs.
2.5-inch
Half slim mSATA
Micro SSD
Single package SSD
- Multi-stack technology
- Embedded technology
Stack structure
mSATA: Micro SATA
Figure 6. Trends in reduction of form factor of client SSDs — SSD products were first released as 2.5-inch-HDD-
compatible devices. The size of SSDs is decreasing in response to diversification in the size of systems. Such
flexibility of form factor cannot be provided by HDDs. The single package SSDs containing the controller and
NAND flash memory by using stack technologies will be available.
Tables 1. SSD classifications and requirements
Class
Operating condition
(at power-on)
Data retention
(at power-off)
UBER
Client 8 hours/day at 40˚C 1 year at 30˚C ≤ 10-15
Enterprise 24 hours/day at 55˚C 3 months at 40˚C ≤ 10-16
UBER (Uncorrectable Bit Error Rate): Uncorrectable error rate (number
of sectors) per total bits read
* Excerpted from JEDEC standard JESD218A
Tables 2. Comparison of specifications of client SSDs and enterprise SSDs
Item
Specification
Enterprise SSD Client SSD
Application Servers, storage systems PCs, notebooks, etc.
Interface SAS, (PCI Express), (SATA) SATA, (PCI Express), (USB)
Form Factor : height (mm) 2.5-inch SFF: 15, 2.5-inch: 7 2.5-inch: 7, 1.8-inch: 5
NAND type SLC, (MLC) MLC
Power source (V) +5/+12 +5 (2.5-inch), +3.3 (1.8-inch)
Performance
Read/write (IOPS) 30 k-100 k/10 k-30 k 10 k-50 k/1 k-20 k
Read/write (MB/sec.) 250-500/220-400 100-500/100-300
Endurance (Bytes) 2 digits PB written per life 2 to 3 digits TB written per life
Data protection in the event of power failure Yes No
End-to-end data protection Yes No
Sector size (Bytes) 512, 520, 528 512
Life (Years) 5 (SLC), 3 (MLC) 1
USB: Universal Serial Bus SFF: Small Form Factor PB: 1015
bytes, TB: 1012
bytes

8. TOSHIBA Storage Products for ICT Society 9
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Enterprise SSDs●
SSDs used for mission critical systems must feature higher reliability, higher endurance, high-speed performance, and
guaranteed sophisticated data integrity, among other functions, to ensure 24x7 continuous operations in heavy workload
environments.
Use of MLC●
For enterprise SSDs, SLC (Single Level Cell (Note 8)
) NAND has been used due to the severe requirements for write
endurance. However, in order to meet the requirement for lower unit price per gigabyte, the use of MLC (Multi Level
Cell (Note 9)
) NAND has been promoted. Adoption of MLC NAND requires increased parallel operations of the NAND flash
memories to improve read/write performance, optimization of ECC mechanism, digital signal processing and error recovery
algorithm to secure effective write endurance and data retention characteristics, and implementation of dynamic write
performance throttling mechanism to manage the endurance and product life.
Future Prospects
The amount of information generated worldwide will continue to increase at an accelerated pace, and as such, stor-
age devices will always be required to realize larger capacity, higher performance, higher reliability, and lower prices. To
meet these needs, Toshiba will continue to promote the development of cutting-edge technologies and the commercializa-
tion of HDDs, ODDs, and SSDs by taking advantage of both its advanced memory technologies as well as its storage
device technologies.
References
(1) Cisco. “Annual Cisco Visual Networking Index Forecast Projects Global IP Traffic to Increase More Than Fourfold by 2014”.
<http://www.cisco.com/web/MT/news/10/news_100610.html>. (accessed 2011-07-15).
(2) TECHNO SYSTEMS RESEARCH ODD Long term forecast Data Y10.xls.,
Tokyo, TECHNO SYSTEMS RESEARCH CO.,LTD, 2011-01-17.
(3) JESD218A: 2011. Solid State Drive (SSD) Requirements and Endurance Test Method.
(Note 8), (Note 9) SLC, MLC
In SLC, one-bit data is stored in a single memory cell. On the other hand, in MLC, multi-bit data is stored in the same cell, but the write
speed is slower and the writable count is lower than that for SLC.
HATTORI Masakatsu
Semiconductor & Storage Products Co.
SUZUKI Hiroshi
ODD Div.
SUGAYA Seiichi
Storage Products Div.