Hard Disk


storage media
optical storage media
magnetic storage media

...

common magnetic storage media as below
hard disk drive: 採證容易,format後還有資料
floppy disks
SSD(solid-state drive): 採證較難,format後就沒資料了
ps:
it can be wiped out by large magnet

....

structure of Hard Disk
cylinder(磁柱): from the tracks composed
tracks(磁軌): a portion of a cylinder, Track's ID is 0(外圈)~1023(內圈)
sector(磁區): disk block portion of a track
refer
http://www.active-undelete.com/hdd_basic.htm

sector
smallest physical storage unit on a hard drive
it is usually 512 byte

ps:
若data為700byte,就會佔用2個sector
ps:
advanced format sector is 4096byte

bad sector
Damaged portions of a disk

...

hard disk addressing
a method of allotting addresses to each physical block of data on a hard disk
主要有以下兩種
CHS(cylinder-head-sector):
LBA(logical block address):

CHS:
區塊必須以硬碟上某個磁柱、磁頭、磁區的硬體位置所合成的位址來指定
常被用在IDE device

LBA:
從0開始編號來定位區塊,第一sector LBA=0,第二sector LBA=1
常被用在SCSI和enhanced IDE device

ex:
disk capacity by CHS
22164 cylinders/disk
80 head/cylinder
63 sectors/track
512 byte/sectors
capacity=22164*80*63*512=57193758720byte
GiB for real capacity(capacity/1024^3)=53.26GiB
GB for manufacturers(capacity/1000^3)=57.19GB

ps
GB and GiB, GB is 1000^3 ; GiB is 1024^3
https://en.wikipedia.org/wiki/Gibibyte

....................

ps:
common optical storage media as below
DVD: single-layer,4GB
HD-DVD: single-layer, 15 GB
DVD-18:15GB
Blu-Ray single-layer: 25 GB
Blu-Ray dual-layer: 50 GB
ps
preventing data is changed, recommendation using media that data only can be written once
ex:DVD+R

ps:
Windows支援兩種CD ROM跟DVD的格式
CDFS
UDF

refer
https://en.wikipedia.org/wiki/Blu-ray
https://en.wikipedia.org/wiki/DVD
http://wenku.baidu.com/view/da7fbcd0360cba1aa811da11.html?re=view

 

2015-10-18 13:23:20發表 2015-10-18 13:23:57修改   

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