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Bad/Unusable areas on a HDD. Common? Do they enlarge?

Can I determine if my hard disk has areas marked off by the formatting process as being damaged and unusable?
- Can I determine the size of any such damaged areas?
- Is it common or rare for HDD?s to have these damaged areas?
- Finally, how likely is it that a damaged area will grow larger over time causing me problems in the future?

I have a Toshiba 40GB HDD (model MK4019GAX) in my 1-year-old Dell 8200 Inspiron notebook. But when I check the HDD under ?my computer?, the total size is stated to be 37.2 GB. So is it likely my HDD has a
damaged area of about 2.8 GB in size, or this it more likely that this Toshiba HDD is only 37.2GB but Toshiba rounds up the number to 40GB for sales purposes?____.

Recently, access to the hard drive would slow down a hundredfold, making this notebook unusable. I ran Dell's HDD diagnostics and it found no hardware problems. I "repaired" the operating system (WIN XP
home) and the HDD began working fine for a day and then became 100 times slower again. I also ran Norton Disk Doctor and scandisk, both of which detected no problems.

A clean install, this time to WinXP Pro, apparently solved the problem. But when doing this clean install I monitored the disk reformatting as it advanced from 1% complete to 100% complete. It took about 1 minute to advance an additional 1% towards completion. But from 24% complete to 28% complete, this reformatting process took 30 minutes, slowing
down by a factor of 7. I suspect that this might be because the WinXP Pro reformatting process (for a clean install) encountered a bad area on my hard disk, and it took 7 times longer to work its way thru that portion of the HDD. But I can't find anyone to confirm my suspicion on this. What else might have been responsible for this slowdown? I did a complete NTFS reformat, not the ?quick? version. It took 130 minutes to complete.

I?m concerned about now spending 10-15 hours loading all my software applications on this notebook. I've been told that bad areas on hard disks often grow in size over time. Is this true?____ Does it occur
rarely or frequently?____ If true and not rare, then perhaps I?m better replacing my HDD now and not taking a chance of a damaged area (if I have one) growing in size and causing my notebook to become
inoperable again in the near future.


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You might try...

In reply to: Bad/Unusable areas on a HDD. Common? Do they enlarge?

running the manufacturer's utilities to check on bad sectors but doubt seriously if that is where your problem lies (matter of fact I notice that you mention that Dell's tool didn't find any).

All drives may have bad sectors but have additionsl sectors to make up for them.

The confusion between binary and decimal math is apparently bothering you regarding drive size. Many hard drive manufacturers use the ISO definition of a "gigabyte," which is "one billion bytes," or "1,000 megabytes." But most people familiar with the binary nature of computers consider a gigabyte to be 1024 megabytes (and that includes an operating system's reporting tools). Thus, a binary gigabyte is somewhat larger than a decimal gigabyte, and that's where the bad blood comes from: Some consumers thought they were getting binary gigs, but actually got decimal gigs. On a large hard drive, the differential adds up.

Progress bars and numbers do not always tell the whole tale of what is happening--don't be reliant on them.

Since you have XP why don't you use the Task Manager to monitor your computer to determine the actual cause of your slow downs. You could really nail it down if you take advantage of other system tools like PERFMON.

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The Microsoft tool ...

In reply to: You might try...

to scan a hard disk is scandisk (full check, including surface check). If that detects not errors, I would trust the hard disk. It's a little bit hidden in Windows XP, but it still exists: see

Edward is fully right about the math and probable other causes for your troubles. But it feels good to know for sure that your harddisk doesn't have bad sectors. My advice for such a disk: replace immediately.


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Perfmon and sysmon...

In reply to: The Microsoft tool ...

are the tools to check on performance issues which he seems to be blaming on hard drive.

CHKDSK will not inform the user where the performance problems actually originate nor provide clues to eliminate the hangups described.

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Flaws exist, but

In reply to: Bad/Unusable areas on a HDD. Common? Do they enlarge?

Manufacturers build in safeguards in the formatting process to work around the flaws. Manufacturing info about bad spots is stored in a disk cylinder that is inaccessable to anybody but the disk itself. In a low level format they may use complex repositioning algorhythms to avoid that spot, or they may just re-vector that bad block to the extra sector that is routinely written on most disks (one per track). In addition format specs frequently call for an extra cylinder or 2 just in case the ones in any particular cylinder are all used up. In addition they go to great lengths to hide this from the user. As long as they still have replacement blocks left to use, and as long as their failure predictions work, they will transparently move the data to a new location BEFORE it becomes unreadable, and the user will be none the wiser. Excessive re-vectoring can cause signifigant disk speed degradation, but MS's SCANDISK will pass the volume as perfect. I watched the scan of a dying disk where the last 1/3 of the disk took twice the time as it needed to scan the first 2/3 of the disk. We replaced the disk, and the user's problems mysteriously cleared up. This is why you should use the Manufacturer's utility to determine the continuing useability of any disk.

And, yes, defects do have a tendency to grow. As long as the growth is not due to oxide particles coming off of the platter surface you're probably ok.

Don't worry, be happy, just understand that all disks will fail. That's why your bank, and your government use RAID technology. And even then they sometimes get burned.

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