why can shutting down improperly crash your harddrive?

[rubix]

What exactly is it about turning off your computer improperly that can cause your harddrive to crash and lose everything on it or cause bad clusters? Does it have something to do with the harddrive's arm scratching the disk somehow? Or maybe something to do with a surge of energy being sent at shut off? Those are my guesses, but I don't know really and need to explain to someone why this happens since it just happened to them. Thanks.

 

[Adrian Tung]

An improper power-down could prevent the read/write heads from reaching their head parking zone in time, causing them to contact with the drive platters and causing physical damage.

Furthermore, if the drive is in the process of writing data, a sudden loss of power will halt the writing process, thus corrupting whatever data that it is writing. If that data happens to be the master file table, everything else on the hard disk gets screwed too.

This is based on my own knowledge, correct me if I'm wrong anywhere though.


atwl

 

[rubix]

Thanks for the reply. Both of these make sense. I never thought of the second though.

 

[Shudder]

There's other things, like the computer is not ALWAYS writing what it should to the hard drive, cacheing it in memory. It could write one part of something you need and not the other, and well, it may not work right when you come back.

 

[chuckieland]

mmm... interesting
it's nice to know

 

[DaddyG]

Adrian, all drives use soft touch thin film read/write heads and have done so for the last 10 years. The days of 'parking' the heads are long gone.

 

[bacillus]

<< The days of 'parking' the heads are long gone. >>


I blame the traffic wardens!

 

[xtreme2k]

Actually

IBM 75GXP has reintroduced 'parking'
check their product informations and you will find out.

Mostly improper shut down usually means there aer some data that is supposed to be written back onto the hdd, but are not really written as they are still in the HDD's Cache memory.

 

[DaddyG]

The IBM Safety ramp unloads the heads when powering down, they 'park' automatically, whenever power is lost. This is not the same as parking the heads.

 

[sharkeeper]

The main problem is with today's larger drive buffers (2MB).

Any data not flushed out to disk during a shutdown is lost!

If you're using Windows9x troubleshooting (disable synchronus buffer commits) which basically delays writes for improved performance, you could be in trouble for shutting down incorrectly!

This affects overclockers especially when first testing a new chip because the system will often crash or freeze.

Cheers!

 

[JJWalker]

Thanks for the info guys.

 

[obenton]

NTFS file system, I understand, is able to recover from these errors, when the computer is rebooted restoring the damaged file to its pre-miswrite state.

 

[Hardnut2K]

There is a patch in the Microsoft update site which prevents the computer being shut down till the hard drive cache is emptied, perhaps this will help a little?