Hardrives versus Cd's?

Question

How can a hardrive fit anywhere from 80 gigs to almost a terabyte, (I have only seen 200 gig, and rumored the terabyte) when a CD is much bigger and max is around 80 megs. Is there more to this than I can figure out, or can a CD really hold more and the producers are limiting them so they can sell more.

Also, if you have the time, tell me if you can how a CD-RW degrades after time, to where a hardrive can be reformatted and partitioned, then reloaded after it degrades, but a CD-RW cannot and even if it can it is still worn to the point of bad programming. Thanks.

Answer 1

The needles that HDDs use to write data onto the drive are able to write on a much smaller portion of the disk than the laser used in CD burners. Hard drives contain a stack of of anywhere from one to six (that's the most I've seen) of what look like very shiny CD's. These Cd's are metal platters that the write head is able to magnetize specific parts of into either the on or off position. Hard drives are able to store such amounts of data on them because each time a higher capacity drive is released all the hardware needed to write data onto the drive comes with it.

Since CD burners have removable media on to which they write all CD burners have to be compatible with all forms of CD's where as hard drives only have to worry about their non removable media. Also the light emitted by the red laser in CD drives has a finite wavelength so it can only write so small before being incompatible with the CD standard.

The manufacturers are not holding out on the CD's maximum capacity rather it is simply pointless to make CD's hold more when DVD, HD-DVD, Blu-Ray, and various forms of flash media are quickly replacing the CD. There are nonstandard CD's which will hold up to 99 minutes (80 is the norm) music but this much data crammed into a limited space leads to quality loss so really the 80min/700MB disks strike the best balance between quality and capacity.

CD-RWs degrade over time because when you burn a CD the laser puts microscopic dents into the CD. When you erase that CD the laser has to burn the media flat again. This process can only be repeated so many times before the media is useless. Hard drives on the other hand hold their data through magnetism and this doesn't slowly degrade the media at anywhere near the rate that a CD-RW does if at all ensuring years of flawless operation. My family's first computer still uses it's original hard drive and that drive is ten years old and counting.

Answer 2

You Sound Like A Begginer To Me So Let's Start With....Terabyte HDD's Are No Rumor The Technology Has Just Not Been Affordable To The Average Home PC User, But Have Been On The Server Market For A While....Secondly CD's Hold 700 MB Or 80 'Minutes' Of Music....Furthermore Producers Arent Limiting Capacities....What Do You Think A DVD Is...It's A Larger Capacity CD...Most People Think DVD Stand For' Digital Video Disk' But It Really Stand For 'Digital Versitile Disk' Whih Is A Second Generation CD...Most People Associate DVD'S With Movies But Did You Know You Can Store Data On There Too.....And ReWritable Medium Degrades Because The Data Is Stored 'On' And Organic Dye Which Being Organic Breaks Down Over Time And With Use....



Apparently No One Else Can Understand Your Question ... Can't Say I Blame Them ... But If You People Would Read Harder You'd See He Is Versusing(lol) The Densities Of The Two Disks ... Not The Reliablilities Or Anything Like That ... I Love When People Just Write Anything They Know About A Keyword They See Without Even Answering The Question ... For Example The People That Answered This Question Just Saw The Word HardDrive And CD And Wrote What They Know About Them Not Actually Answering The Question...Yahoo!!Answers People ... Not Yahoo!Look At How Much Bad Info I Can Give Out.....Ok Im Done Know....



I Find It Friggin Amazing That All These People That Obviously Have The Internet Are So Misinformed ... Don't Know How A CD-RW Works ... 'Dents' 'Bends Em Back' ... Omg...Stick With Me Buddy I Won't Steer You Wrong These Other Doofs Don't Know Nuttin'......

Answer 3

1) Most Cd's are only a single surface, a HDD has multiple platters in it.
2) A CD is an optical surface, it spins slower and the tracks are further apart.
3) Magnetic media is inherently easier to manufacture and the data is easier to manipulate.
4) A CD is 'Burnt' literally!! so each time the media is erased and rewritten you lost a few microns and a few particles. (A HDD only has it's magnetic particles re-arranged - it is not a lossy system - although eventually they do wear out).
5) A HDD is much faster to access because it also has multiple heads so the head actuator only has to travel a small distance to cover the entire platter. It also is likely to have a RAM buffer too, to speed up transfer via the DMA to the memory or whichever device requires it.

These are just some of the things which should help you understand the reasons why. - And yes TeraByte disks do exist.

Answer 4

Hard disks are read by variatons of the magnetic field on their surface. They have such a dense amount of information packed into them that they must be manufactured in ultra-clean rooms so that no dust contacts the surface. If you ever open your HDD, then it becomes unreadable.

CD can tolerate a fair amount of abuse, and still be read by your computer because the optical data encoded in them is less dense. That's why hard disks can have more information in them.

I don't understand what you mean about a hard disk being reloaded after it degrades. CD-RWs degrade because they are written by a laser that etches grooves into their surface. You can only write to them so many times before they wear down.

Hard disks can be written to indefinately because the physical surface of the disk is unchaged. Only a magentic charge is applied. But, hard drives do not last forever. In fact, they are some of the most fragile components of computers.

Answer 5

HDDs are more reliable in terms of data.