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wayne384
02-19-2002, 02:08 PM
Hi,
As we know, when MS FDISK is asked to partition a hard drive (HDD), it spends a good deal of time “Verifying drive integrity”, less on small drives and substantially more on large (60GB) drives. Well, because of a problem I was experiencing, having MS FDISK create an extended partition on a 60GB HDD, I wanted to see just what area of the disk was being scanned while MS FDISK was “verififing drive integrity”. Here is what I uncovered (literally). I took the top cover off an old working HDD (2.5 GB) to watch the arm (head).

When the MS FDISK was verifying, the arm went to the approximate location that one would expect, for a primary partition, the arm (head) stayed at the edge of the platter (Sector 0), for a 50% extended partition, the arm went to the 50% portion of the usable disk area, 80%, 80% etc. It stayed there while doing the checks! Sooo... MS FDISK does NOT scan or search the hard drive while verifying!

On the other hand, “format” does search the entire usable area of the disk, if there is one volume, otherwise it scans the area where the concerned volume would be expected to be. All “measurements” were made by “eyeball” and a plastic ruler - so this is not the final word, but the observations created “a need to know.”

What is MS FDISK doing while it is “Verifying drive integrity”? Can anyone shed some light on this? Is it calculating CHS/LBA values??

Western Digital’s “LifeGuard”, PQ's Partition Magic, Free FDISK and other such partitioning programs apparently make the same partitions, but do not perform the verifying function... apparently the verifying is not that critical.

Any insight you can give me would be appreciated. Thanks for your time.


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Wayne
wgplumtr@lasd.org

mjc
02-19-2002, 02:14 PM
I always thought that fdisk was reading/writing to certain areas or groups of areas....hmmm, interesting.

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

bassman
02-19-2002, 07:09 PM
Hey Wayne, welcome to the forums http://www.PCGuide.com/ubb/cool.gif
I don't have a straight answer as to what it is doing, but maybe a clarification of terminology.
Fdisk performs a Drive integrity test.
Scandisk performs a Surface integrity test.
Not sure what the true definition of these is, but that may explain why you saw little head movement http://www.PCGuide.com/ubb/wink.gif

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Waiting patiently for the future to arrive. Frank's Place (http://dreamwater.net/tech/frankscomp/)

pentachris
02-19-2002, 08:24 PM
I've proved before on these forums that I thought I understood concepts that I really didn't, but I'll throw this out anyway... http://www.PCGuide.com/ubb/rolleyes.gif

Would a "drive integrity test" maybe just check to see if any sectors had been previously marked by scandisk as "bad" so that they can be re-marked appropriately on the new drive? Would information on bad sectors be stored at the beginning of the partition?

edit: a few hasty google searches (before I leave work for the day http://www.PCGuide.com/ubb/smile.gif) seems to indicate fdisk performs chkdsk. See what it does here (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q187941).
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Some mistakes are too much fun to make only once.

[This message has been edited by pentachris (edited 02-19-2002).]

wayne384
02-20-2002, 03:18 AM
Additional observations:

#1 Write 0's to HDD time: 17 minutes Arm went from Cylinder 0 to last cylinder.

#2 FDISK: Time: 12 sec for each "Verifying Drive Integrity 0-100%" 12 sec.
Arm remained at cylinder 0

#3 FORMAT: time: 5 min 45 sec. Arm atarted at cylinder 0 and progressed to last cylinder.

#4 CHKDSK: Time: 2.5 seconds. Arm stayed at cylinder just greater than 0.

#5 SCANDISK: Time: 8 seconds. Arm stayed at cylinder just greater than 0. Only the file structure was run. Surface test was not run.

Disclaimer: All time measurements were made by observing a second hand on a cheap watch, cylinder gustimates were made by relative positions using "eyeballometrics"

Not sure what these mean or add to figuring what FDISK is doing, but here they are.



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Wayne
wgplumtr@lasd.org

steveo
02-20-2002, 10:41 AM
weird, but neat stuff you got going on there. Most times my brain goes numb when doing fdisk functions. Now I have something to think about...heh

bassman
02-20-2002, 11:27 AM
That is pretty cool Wayane, I know it is something a lot of us have wanted to do just to see it.
Thanks for the info http://www.PCGuide.com/ubb/wink.gif

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Waiting patiently for the future to arrive. Frank's Place (http://dreamwater.net/tech/frankscomp/)

wayne384
02-20-2002, 11:52 AM
Another Question,

Is there a program that could run in the background, or an IDE hardware attachment that could tell which cylinder (and/or head/sector) the hard drive is reading? This would have to be independent of any other program that would also be operating. It would seem a connection thru/to the IDE cable is certainly possible. Does such a "thing" exist, and if so, is it afforadable??

Inquiring minds just want to know!

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Wayne
wgplumtr@lasd.org

mjc
02-20-2002, 12:46 PM
I'm sure if something like what you want exists it wouldn't be affordable, it sounds like something that drive manufacturers would have/use or data recovery services (and we know that they aren't cheap...I guess to pay for all their fancy equipment)

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.