Secondary/primary/tertiary storage (part 2/2)
Terminology:
-storage media is the actual thing that holds the data (optical discs)
-storage device is the thing that reads/writes data to media
(HDDs, optical drive)
Optical discs
Optical discs are cheap secondary storage
Optical discs are things like CDs, DVDs, Blu-Ray discs.
They come in 3 forms:
Read-only:
CD-ROM/DVD-ROM/BD-ROM
Write-once:
CD-R/DVD-R/BD-R
rewritable:
CD-RW/DVD-RW/BD-RW
Optical discs use is declining:
-Internet speeds are increasing so streaming and downloading services(netflix/itunes/steam) took their job.
-Modern devices(phones, tablets don't have optical drives)
Flash storage devices are better than DVD-R and DVD-RW because DVD-R/DVD-RW have low-capacity per disc, very slow read/write speed and poor reliability of RW discs.
Advantages:
-cheap
-portable
-won't be damaged by water/shocks
Magnetic Tapes:
Magnetic tapes are used for archiving
Has a much greater storage capacity than HDDs.
Low cost per GB
Often used by large organisations to store huge amounts of data.
Cassettes require tape-drive for read/writing
Tape is read/written sequentially(read/written from the beginning to the end. So tape is slow when it needs to find specific data, but has a fast read/writing speed.
slowest read/write speed: optical disc
Lowest capacity: optical disc
Fastest read/write speed: SSD
Cheapest cost per GB:Magnetic tape
Priciest cost per GB:SSD
Highest capacity: magnetic tape