Flash memory

Hard Disk DriveM a g n e t i c T a p e s

Compact disc/DVD/Blu-Ray

Memory Stick

can be electrically erased and reprogrammed

storage and transfer of data between computers and other digital products

no power is needed to maintain the information stored in the chip

fast read access times (although not as fast as volatile DRAM memory used for main memory in PCs) and better kinetic shock resistance

when packaged in a "memory card," it is enormously durable, being able to withstand intense pressure, extremes of temperature, and even immersion in water.

Very fast access to data. Data can be read directly from any part of the hard disc (random access). The access speed is about 1000 KB per second

A typical desktop HDD, might store between 120 and 300 GB of data (based on US market data), rotate at 7,200 revolutions per minute (RPM) and have a media transfer rate of 1 Gbit/s or higher. (1 GB = 109 B ; 1 Gbit/s = 109 bit/s)

The highest capacity HDDs are 1 TB .

Hard Disk Drive

Flash Memory

Much faster to access than a floppy but it is currently slower than a hard disc.

Easily damaged by being scratched

The data cannot be edited once it has been written to the CD-R.

CD-R and CD-RW are swappable storage media alternatives

Like a ll fla s h me mory de vic e s , fla s h drive s c a n s us ta in only a limite d numbe r o f write a nd e ra s e c yc le s be fore fa ilure

Mos t US B fla s h drive s do not inc lude a write -prote c t m e c h a nis m, a lth oug h s ome h a ve a s witc h on th e h ous ing o f th e drive its e lf to ke e p th e h os t c ompute r from writing or modifying da ta on th e drive

A dra wba c k to th e s m a ll s iz e is th a t th e y a re e a s ily m is p la c e d, le ft be h ind, or oth e rwis e los t. Th is is a pa rtic u la r prob le m if th e da ta th e y c onta in a re s e ns itive

Limite d c a pa c ity, US B fla s h d is ks top out a t a bout 64 G B

The Importance and need of backup: Is to restore a state following a disaster (called disaster recovery). To restore small numbers of files after they have been accidentally

deleted or corrupted. The more important the data that is stored on the computer the greater

the need is for backing up this data. B ackups will fail for a wide variety of reasons. A verification or

monitoring strategy is an important part of a successful backup plan. It is good to store backed up archives in open/standard formats. This

helps with recovery in the future when the software used to make the backup is obsolete. It also allows different software to be used.

Internal Memory VS Backing Storages

It is always faster to access data from internal memory than from backing storage.

When programs are run or data files are loaded the contents are copied from the backing storage to the internal memory of the computer

Internal memory is much smaller than backing storage

The structural is simple Its referred to as Immediate

Access Storage (IAS) because the hardware can access the data so quickly compared to data in backing storage

Data stored in internal memory is lost when the computer is turned off but data stored in backing storage is retained.

Data stored in backing storage is permanent so it is NOT lost when the computer is turned off

The access speed is about 1000 KB per second

It is used to store: The operating system (e.g. Microsoft® Windows) Applications software (e.g. word-processor, database, spreadsheet, etc.) Files such as documents, music, video etc