Storage Devices
and Media
Backing-Up Data
•
Backing up refers to copying files or data into a different medium in case of
damage or loss of original copy.
Why do we back up data?
•
To safeguard (protect) against loss of data.
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To safeguard against damages caused by hackers.
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In case files need to be sent elsewhere, to protect the original format of
files.
Magnetic tape drives
Advantages:
•
They are generally less expensive /cheaper than hard
disk drives.
•
It is a very robust (strong) technology.
•
They have a huge data storage capacity.
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The data transfer rate is fast.
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Prolonged data access times (uses serial access).
Disadvantages:
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Prolonged data access times (uses serial access).
•
When updating, another tape is needed to store the
final updated version.
•
They are affected by magnetic fields. A strong field can
corrupt data stored on the tape.
Fixed Hard Disks/Drives
• Used to store the OS, systems software and working data/files.
• Storing applications files.
Advantages:
•
•
They have a very fast data transfer rate and
fast access times to data.
Disadvantages:
•
It can be fairly easily damaged.
•
They have many moving parts which affect
overall reliability.
•
Their read/write operation can be quite noisy
when compared to solid-state drives.
They have a very large memory capacity.
Portable Hard Disk Drives
•
Can be used as a backup system to prevent data loss.
•
It can be used to transfer data/files/software between computers.
Advantages:
•
Data access time and data transfer rate are very fast.
•
It has a very large memory capacity.
•
It can be used as a method of transferring information between computers.
Disadvantages:
•
They can be easily damaged if user accidentally drops it or doesn’t correctly shut
down the drive after use.
•
The data transfer rate is not as fast as for fixed hard disk drives.
Solid State Backing Storage
Holds data on media that do not have any moving parts
Solid State Drive
Advantages
They are more reliable as they have no
moving parts.
They are considerably lighter, suitable for
laptops.
They have a lower power consumptions.
They run much cooler than HDDs.
Because of no moving parts, they are
very thin.
SSD data access time is only 0.1
milliseconds compared to 10 milliseconds
for HDD.
Data transfer speed for SSDs is also much
faster than for HDDs.
Disadvantages
More expensive than magnetic hard
disks.
Smaller storage capacity than
magnetic hard disks.
Pen Drives (Memory sticks)
Used for sending files between computers or using it as a
backing store
Advantages
Disadvantages
Very compact and portable media.
Very robust.
Cannot write protect the data/files by
making it ‘read-only’.
Does not need additional software to
work on most
Easy to lose (due to the small physical
size).
computers.
They are not affected by magnetic
fields.
The user needs to be very careful
when removing a memory stick from
a computer - incorrect removal will
corrupt the data on the memory stick
and make it useless
Flash Memory cards
Different types of memory cards:
SD cards (secure digital card)
Micro SD cards (Micro secure digital)
XD cards (extreme digital card)
CFast card (compactfast card)
Uses:
Storing photos on digital cameras. Used as mobile
phone memory cards.
Used in MP3 players to store music files.
Used as a backing store in hand-held computer
devices.
Flash Memory Cards
Advantages
Disadvantages
Very compact.
Because of no moving parts, they are
very durable. They can hold large
amounts of data.
Expensive per gigabyte of memory
when compared to HDDs.
Have a lower storage capacity than
hard disks.
Compact cameras and smartphones
are able to read and write memory
cards allow the user to transport large
collections of photographs, songs etc.
Have a finite life regarding number of
times they can be read from or
written to.
Memory cards, specifically the micro
SD card, are the smallest storage
devices available; this means they
are more likely to be lost, stolen or
damaged.
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