speichermedien Flashcards
disk blocks
preamble is important ,
Preamble,Data,ECC
virtual geometry
it decreases the number of sectors but increase the the number of heads
LBA
USE logical block addressing system where each block is assigned a unique number in LBA:
shortes seek first
Disk schedulling algorithm to determine the order in which disk I/O requests are processed.
Goal:minimise seek time
advantage: minimised seek time
disadvantage:starvation since only tasks close to head is served
edges are disadvantaged
Headmove
Head moves as long as possible in the same Direction
minimize head move
Boots from Hard disk
master boot record
-> saved in the first block the plate
->contains Bootloader code and Partition Table.
support up to four primary partitions or 3 primary and one extended partition containing multiple logical partitions
hard disk partitions
Division of a hard disk drive /solid state drive into seperate,distinct sections.
Each Partition can function as an independent storage unit,allowing multiple file systems,operating systems.
Primary partitions-> up to 4 primary partition ->host operatinf systems and bootable
CD-ROM
compact Disk -read only memory
data readable by computer but can not be written or modified
data encoding:pits and land: data is encoded in the form of tiny indentation(pits) and flat areas(lands) on the disc surface
laser Reading(laser can read pits and land)
CD Rom sectors
preamble (byte 16)(sync,header) –Data(2048)-ECC(288)(error correction code)
CD-ROM Reading Position
Data is on a continuous Spiralarranged->spiral divide itself in sectors,
->find a sector
Access times are much worse than on hard drives
CD-R
layer of cdr- printed label-protectiv laquer-reflective gold layer-dye layer
VTOC -> Volume Table of Contents
transer data in one gowrite
multisessiom cds
one cd-r can contain several sense
advantag-flexible data addition
efficient use of space
drawbacks-compability issues
space overhead- >each new Session requires its own lead in and lead out areas
complexity: managing multiple sessions and ensuring data integrity accross session can be complex
RAID
Redudant Array of Indepedent Disks
goals:
Increase Data Security
increase the transfer rate
Construction greater logic drives
exchange of defective plates while operation
cost reduction through smaller and cheaper plates.
Hardware RAID
Use Dedicated Hardware Controller to manage the RAID array.This controller can be a standalone Raid card installed in a PCI
Advantage Raid
->Performance- offloading RAID operations to the dedicated controller reduces the load on the host CPU
reliabilty
3.advanced Features
support for higher end Raid levels and configuration
Disadvantage of Hardware RAID.
1.cost -> Hardware RAID
2.complexitty
software against harware
implementation less hoch
performance niedrig hoch
cou las am host hoch niedrig
platform/betriebsabhangig ja nein
software raid
uses the host system’s CPU and operating system to manage the raid array without needing dedicated hardware.it is a cost effective solution that provides flexibilty and ease of management.
1.cost effective
2.flexible
3.easy management
disadv
performance imopact
system dependency
3.limited advanced features
parity bytes
detecting single bit error
if the number of 1 bit is even add 0
1 bit odde add 1
hamming distance: h=2
-> can detect one bit error
raid level
raid 0 -> data divided accross mulriple
raid 1-> data duplicated (mirrored) (high fault tolerence .. storage down
raid 2:hamming codes
raid 3->( striping with parity) -> data and parity information are striped across multiple disks ->( good balance of performance and redundancy can withstand, the failure of one disk)
raid
