Secondary Storage (Optical, Magnetic, Solid-State & Cloud)

Summary

This video script delves into secondary storage, emphasizing its necessity for long-term, non-volatile data retention. It explores various storage mediums, including optical, magnetic, and solid-state drives, each with its unique characteristics like speed, durability, and reliability. The script also touches on cloud storage, highlighting its accessibility, portability, and the potential cost benefits for large-scale users. The discussion aims to educate viewers on the importance of evaluating these factors when choosing a storage solution.

Takeaways

• 💾 Secondary storage is essential for long-term, persistent, non-volatile storage that retains data even when the power is off.
• 🚀 Secondary storage devices like hard drives and SSDs require controllers and do not connect directly to the CPU, unlike main memory like RAM.
• 🔍 When evaluating secondary storage, consider key factors such as speed (both reading and writing), durability, and reliability.
• 📀 Optical storage uses a laser to read data from pits and lands on a disk, representing binary data, and is limited in capacity but portable and relatively durable.
• 🧲 Magnetic storage, like hard drives, uses electromagnets to read and write data by magnetizing or demagnetizing parts of the disk, offering large capacities but is less durable and generates heat.
• 💿 Solid-state storage (SSDs) uses flash memory with digital circuits and has no moving parts, resulting in faster read/write times, higher reliability, and less heat production, but at a higher cost per unit of storage.
• ☁️ Cloud storage is not a physical storage medium but a service that allows data to be stored on remote servers and accessed over the internet, offering portability and potentially lower costs for large-scale data storage.
• 🔄 SSDs do not require defragmentation, a process used in magnetic storage to optimize data storage by consolidating fragmented files.
• 💡 The choice between different storage technologies often comes down to balancing speed, capacity, cost, durability, and the specific needs of the user.
• 🌐 Cloud storage providers may offer multiple versions of files, enhancing data durability, but the reliability of the service can vary depending on the provider.

Q & A

What is secondary storage and why is it essential for a computer system?

Secondary storage refers to any memory device not directly connected to the CPU, such as hard drives and optical disks. It is essential for long-term, persistent, and non-volatile storage, meaning data is retained even when the power is turned off. Without secondary storage, data would be lost every time the computer is turned off, and there would be no way to retain instructions or data for future use.

How does the speed of secondary storage differ between reading and writing?

The speed of secondary storage, often referred to as read/write speed, can vary between reading and writing data. Typically, if a device is quick at reading data, it is also quick at writing data, but they are not always the same. The script emphasizes that speed is an important factor when evaluating secondary storage mediums.

What does durability mean in the context of secondary storage?

Durability in the context of secondary storage refers to how much physical damage the storage medium can withstand, such as drops or impacts. It indicates whether the storage medium is likely to become completely unusable after such incidents.

How do optical storage devices read and write data?

Optical storage devices read data by shining a light on the disk surface, which has variations in height representing binary data (pits and lands). The reflection angle differs based on whether the spot is a pit or a land, allowing the reader to determine if it represents a 1 or a 0. Data is written using a laser that burns pits into the disk.

What are the typical capacities and durability of optical storage like CDs and DVDs?

Optical storage like CDs and DVDs typically have small capacities, usually around a gigabyte, and are not suitable for storing large amounts of data. They are fairly reliable and durable under normal conditions but can be easily damaged by scratches or mishandling.

How does magnetic storage work, and what are its advantages and disadvantages?

Magnetic storage uses read/write heads with electromagnets to magnetize or demagnetize parts of the disk, representing binary data. The disk spins, and the read/write head can detect the magnetic state to read or write data. Advantages include large capacities and relatively low cost. Disadvantages include being less durable due to the mechanical nature, prone to damage if dropped, and generating heat and noise during operation.

What is solid-state storage, and how does it differ from mechanical storage?

Solid-state storage, such as SSDs, uses flash memory and digital circuits for data storage without any moving parts, unlike mechanical storage like hard drives. This makes SSDs faster, more reliable, silent, and producing less heat, but they are typically more expensive per unit of storage.

Why is defragmentation not needed in solid-state drives?

Defragmentation is not needed in solid-state drives (SSDs) because they do not suffer from the issue of data fragmentation that occurs in mechanical hard drives. In hard drives, data can become scattered across the disk, requiring defragmentation to improve access speed. SSDs manage data differently, so this process is unnecessary.

What is cloud storage, and how does it relate to other storage types?

Cloud storage is a service that allows data to be stored on multiple servers in a remote location, accessed via the internet. It does not represent a unique storage type but rather utilizes other storage technologies like magnetic or solid-state drives. Cloud storage offers portability, as files can be accessed from anywhere with an internet connection, and can be more or less cost-effective depending on the scale of use.

How does the reliability of cloud storage services compare to other storage mediums?

Cloud storage services are generally considered reliable, especially when provided by well-established companies. However, the reliability can depend on the specific provider and their infrastructure. While most providers aim for high uptime and data redundancy, some services may experience downtime or data loss, which could be a concern for users.

What are some factors to consider when evaluating secondary storage mediums?

When evaluating secondary storage mediums, factors to consider include speed (read/write), durability, reliability, capacity, cost per unit of storage, portability, and the need for an internet connection (for cloud storage). Each storage type has its advantages and disadvantages in these areas, which should be weighed based on the intended use and requirements.

Outlines

00:00

💾 Secondary Storage Essentials

This paragraph delves into the concept of secondary storage, which refers to memory devices not directly connected to the CPU. Unlike main memory (RAM), secondary storage requires data to pass through controllers and lacks a direct channel to the CPU. It's crucial for long-term, persistent, non-volatile storage, ensuring data retention even when the power is off. The paragraph introduces key terms for evaluating secondary storage: speed (both reading and writing), durability (resistance to damage), and reliability (likelihood of failure over time). It also touches on the importance of these storage mediums, highlighting that computers rely on them for permanent data storage and instruction retrieval.

05:02

📀 Exploring Secondary Storage Technologies

The second paragraph explores various secondary storage technologies, starting with optical storage, which uses pits and lands on a disk to represent binary data (1s and 0s). Data is read using a laser, which detects variations in the disk's surface to interpret data. Writing data involves burning pits into the disk with a laser. Optical storage, such as CDs and DVDs, is noted for its portability and durability but is susceptible to damage from scratches. Magnetic storage, exemplified by hard drives, uses electromagnets to read and write data by magnetizing or demagnetizing parts of the disk. Hard drives offer large capacities and are cost-effective but are less durable and can fail over time. The paragraph also mentions the noise and heat generation associated with mechanical硬盘. Solid-state storage, like SSDs, is highlighted for its speed, reliability, and lack of mechanical parts, making it silent and heat-efficient. However, it's more expensive per gigabyte compared to hard drives. The paragraph concludes with a brief mention of cloud storage, which relies on remote servers and internet access, offering portability and the potential for data versioning but requiring a stable internet connection.

Keywords

💡Secondary Storage

Secondary storage refers to memory devices that are not directly connected to the CPU, requiring data transfer through controllers rather than direct CPU buses. This concept is fundamental to the video's theme as it sets the stage for discussing various types of storage mediums. The script mentions that secondary storage is essential for long-term, persistent data retention, which is critical for computer systems to maintain data integrity when power is cycled.

💡Non-volatile Storage

Non-volatile storage is a type of storage where data is retained even when the power is turned off. The video emphasizes the importance of non-volatile storage for computer systems, as it ensures data is not lost during power outages or system restarts. This is a key feature that distinguishes secondary storage from primary, volatile memory like RAM.

💡Speed

In the context of the video, speed refers to the reading and writing capabilities of storage devices. The script notes that while reading and writing speeds are not typically the same for a device, a device that reads data quickly often writes data quickly as well. Speed is a crucial factor in evaluating storage mediums, as it directly impacts the performance of data access and manipulation.

💡Durability

Durability, as discussed in the video, pertains to the physical robustness of storage devices, particularly their resistance to damage from drops or impacts. The script uses the example of hard drives, which are surprisingly unreliable in terms of physical durability, often failing after a few years of use. Durability is an important consideration for long-term data preservation.

💡Reliability

Reliability in the video script refers to the consistency and dependability of storage devices over time. It is highlighted that hard drives, despite their large capacity and low cost, are not very reliable due to their mechanical nature, which makes them prone to failure. Reliability is a key factor in choosing storage solutions, as it affects the trustworthiness of data storage.

💡Optical Storage

Optical storage is a type of secondary storage that uses laser technology to read and write data. The video explains that data is stored on optical disks as variations of pit and land patterns, representing binary data. Optical storage is characterized by its portability and durability but can be easily damaged by scratches. Examples in the script include CDs, DVDs, and Blu-ray disks.

💡Magnetic Storage

Magnetic storage is another form of secondary storage that uses electromagnets to read and write data. The video describes how data is stored on magnetic disks by magnetizing or demagnetizing areas on the disk. This type of storage is known for its large capacity and relatively low cost but is less durable and more prone to mechanical failure compared to solid-state storage.

💡Solid-State Storage

Solid-state storage, specifically solid-state drives (SSDs), is a non-mechanical form of storage that uses digital circuits and logic gates. The video points out that SSDs are faster than hard drives and more reliable due to the absence of moving parts. They are also silent and produce less heat, although they can be more expensive per unit of storage compared to magnetic storage.

💡Cloud Storage

Cloud storage is a service that allows data to be stored on remote servers and accessed over the internet. The video script mentions that cloud storage is not a unique type of storage but rather a service that utilizes other storage technologies. It is highlighted for its portability and the ability to access data from anywhere with an internet connection, although it requires a reliable internet service.

💡Defragmentation

Defragmentation is a process mentioned in the video that involves organizing data in a storage device to improve efficiency. The script explains that while traditional hard drives require defragmentation to optimize data access, SSDs do not due to their different data management mechanisms. This process is relevant to the discussion of storage optimization and performance.

Highlights

Secondary storage is essential for long-term persistent storage and must be non-volatile to maintain data when power is off.

Secondary storage devices like hard drives require controllers and cannot connect directly to the CPU.

Key evaluation factors for secondary storage include speed, durability, and reliability.

Speed in secondary storage refers to both reading and writing data, which are often different but related.

Durability pertains to the physical robustness of storage devices, such as resistance to damage from drops.

Reliability indicates the expected lifespan and the likelihood of the device failing over time.

Optical storage uses laser technology to read data from variations in disk surface height.

Magnetic storage, such as hard drives, uses electromagnets to read and write data by magnetizing disk surfaces.

Solid-state storage, like SSDs, uses digital circuits and has no moving parts, offering faster read/write times.

Cloud storage is a remote data storage service accessed via the internet, often using magnetic or solid-state storage.

Cloud storage providers may offer versioning, allowing users to access and revert to older data versions.

The reliability of cloud storage can vary, with some services potentially experiencing more downtime.

Portability is a significant advantage of cloud storage, as data can be accessed from any internet-connected device.

Costs for cloud storage can be influenced by economies of scale, with larger companies potentially benefiting more.

Environmental considerations may favor cloud storage due to potential energy cost reductions for large-scale data storage.

For personal use, cloud storage might be more expensive due to billing models that charge for ongoing storage rather than a one-time purchase.

Transcripts

when I look at secondary storage which

is any memory device not directly

connected to the CPU so main memory like

RAM has its own buses that connect

directly to the CPU secondary storage on

the other hand has to go through in

Palpa Challenger has to go through

controllers it can't it hasn't got a

direct channel to a CPU and you need

secondary storage so you've got

long-term persistent storage ie

non-volatile storage meaning the data is

kept when power is turned off you can't

have a computer system without having at

least a connection even a very first

instance to secondary storage you need

to have a permanent store of dates you

can't lose your data every time you turn

the computer off because how would you

turn on again you need a place to get

your instructions from when you're

evaluating secondary storage mediums

which we're going to look at Miss video

there are some key words you should

really be using some buzzwords or impact

as you buy talk about how meant to its

by defining each one speed image context

phone means both reading speed and

writing speed so reading data from the

devices and also writing data for the

devices but usually they're not the same

but usually if one device is very quick

to read data it's also going to be very

quick to write data usually durability

is how much damage you can kind of

sustain if you dropped it for example is

it going to complete smash not that I'd

advise doing of anything and also

reliability isn't going to work overtime

is there a drop of foam where it should

probably or

on average stop working for example hard

drives are surprisingly unreliable in

the sense we often stop working a couple

of years into they into their life if

you look at the average of over major

brands they drop off quite quickly quite

worryingly quickly actually so really

you should be using these words when

you're evaluating secondary storage

let's not look at some secondary storage

technology the first one being optical

storage which stores with data by Royal

data stored as binary so I have a 1 or 0

there in stores it has variations of

height on the disk surface so the disk

is full of almost invisible pits and

loud zap it is a little divots and

Landers of C wears flats

so app it might represent a zero alarm I

represent a 1 in binary and so when

lights shined on this disc in a reader I

Steve again when light is shined on a

land a flat bit it just gets reflected

up so it's quite a standard reflection

of that point but if it's a pit it

bounces off a different angle so it can

tell when it reads this whether or not

it's representing a one or a zero that's

how you read data off a optical disk but

you write data with a laser but burns

fees variations burns were pits into the

disk so a mini evaluation per unit in

terms of a single DVD a single CD they

have a small capacity you don't get you

don't exactly have like 50 movies stored

on a single CD because you can't make

capacities not by large usually it's

around a gigabyte in a kind of typical

one obviously for like blu-ray it would

be more they are fairly reliable and

durable but can be easily damaged so

durable is a kind of funny one in this

context because you can kind of look

after a CD quite easily but then you can

damage it very easily if you know I mean

so scratches of course but we are very

portable very easy to transport carry

you can store loads of them very easily

let's unlock a magnetic storage which

instead of using a laser and a light to

read write data this uses read/write

head server containing electromagnets

and so instead of a little divot being

created in the disk like optical parts

of the disks are either made magnetized

or demagnetized by the electromagnets in

this little read/write head here and so

the disk spins and it can make parts of

it magnetized with a magnetized when

you're writing and it can tell if it's

magnetized or demagnetized when it's

reading this is a hard drive where hard

drivers come at the whole unit whereas

obviously the disk for hard disk is no

surprises for disk and in terms of

evaluation they are comparatively have a

very large capacity you can have

terabytes of magnetic storage of to

about hard disks and cheap compared to

other long-term storage mediums they're

usually quite reliable but as

before they actually often stopped

working after a certain amount of time

but we're not very durable you can

easily break them if you dropped it you

would smash four discs can break it and

they're not very important with it

generally because another example which

isn't news anymore is cassettes a

magnetic tape which would be very

portable and also you can have external

disk drives which are also magnetic but

you know generally the type of go inside

your computer aren't possible at all

because they are mechanical this is a

mechanical disc obviously it's spinning

around

it is often quite noisy and also

generate heat which is a major

disadvantage but usually it's the

capacity and the cheapness of it but

kind of over wall so you have a

disadvantages the third type of storage

when we're looking at is solid-state

storage and this is a solid-state drive

an SSD and this is a type of flash

memory which is non-mechanical so hasn't

got a little spinning disk in it like

the other two this consists of just

digital circuits logic gates for keep

datum and you can change your masters

for storages we can't really talk about

how will be work exactly because it's

too complicated

it's just loads of little circuits you

kind of value it from quite nicely they

are a lot faster they read write times a

lot faster than hard drives for example

but per capacity or per unit sorry very

lot more expensive so 128 gigabyte SSD

might cost the same as a terabyte hard

drive if I'm right been a while since

I've bought either one of them they are

quite reliable compared to other types

because there are no mechanical was less

we can go wrong in that sense if you

don't know this means don't worry too

much but we don't need defragmentation

this will be covered at some future

point where and this is where data's

kind of shuffled around so it's more

efficient because they can often get

misplaced and spread about in a hard

drive but we don't need to do it with an

SSD there's another much smaller

capacitive and magnetic hard disks

because they have because they're more

expensive sorry they are silent but we

don't really produce much heat which is

another advantage you might want to talk

about mostly because a majority people

can't afford to have a or two terabyte

lots of SSDs

my computer a SSD is often use to store

the operating system because it's very

quick to load so when you turn the

computer on it's very fast to load but

then will have most of our data stored

in a mechanical magnetic hard drive for

final medium when we're looking at is

cloud storage it comes up all the time

and exams it's really a one of Examiners

favorite topics cloud storage this is

where data stored on multiple servers in

a remote location and you access it

across the internet and this is whether

not an out because it's not its own

storage in its own right it's not a

unique type of storage they use it

you've sadly to be magnetic and still

will use something else but now because

of a speed and because it is getting

cheaper they'll increasingly use

solid-state storage so this isn't its

own type of storage it will use the

other two as I say you'll access

customer through the internet through a

web-based API application programming

interface just a way to access your data

online usually or for a nap often so now

for a quick evaluation these are just

suggested points whatever way as of the

other ones I've shown you so far lots of

things you can talk about here these are

just pointers often multiple versions

are kept by cloud storage providers so

if you need to go back to an old version

that's usually okay so that's kind of

counts for durability in my sense but

depending on who you choose the service

might not be reliable I would say most

cloud storage providers are reliable

because if they weren't first of all

it's huge startup costs you become a

cloud storage providing initial

Microsoft of Google it's hard to just

start one but so it usually they are

reliable but for may not be the service

may be down quite a lot which is quite

worrying so you wouldn't want to use

that clearly very very very portable

files can be accessed anywhere on the

internet so totally portable but you

need internet connection that is another

the validation point you can make a

third more niche point is about four

costs mainly due to economies of scale

large companies using cloud storage

providers to store all their company's

data may be cheaper and probably reduce

energy costs which is a really nice

environmental evaluation point but for

smaller users it may be more expensive

because the model be storing that much

data might get billed monthly as opposed

to just a one-off pain

for larger hard drive for example so for

the first free technologies we looked at

make sure you understand how they work

roughly the solid-state ones are

slightly harder to talk about but they

are just digital circuits you won't be

expected to know more from that but

clerestory just slightly more about

evaluation but they do use magnetic and

now increasingly solid-state storage