Damaged external drive partially slow after reformat

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Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 12:19 pm

Hi, I would need some suggestions over an issue.
I have 2 external drives which have some bad sectors, model Samsung G2 portable of 640 GB. Both are no longer under warranty as they are more than 3 years old.
Naturally, I moved all my important data on another drives. But, since the number of bad sectors is (or, more exactly, was) not very high, several hundreds at most, I intended to keep using them (for "junk" data, which I would not care about if it is suddenly lost) until they would simply fall apart.

I had once a hard drive (internal) which showed bad sectors and I was able to use it intensively for more than 18 months after the first bad sectors appeared.
But here is a little problem: I reformatted both drive in order to have the bad sectors marked as "bad" and re-allocated. But, while the bad sectors dissappeared after the reformat, the reformatting resulted in several sections of the drives (tipically of 5-10 GB in size) becoming extremely slow.
One of the drives showed bad sectors almost 2 years ago. Reformatting removed them and no new ones appeared, but there are small parts of the drive where the writing speed slaws to a crawl (up to 1-2 MB/s). The reading speed is fine over the entire drives.
The second drive (which went bad just a week ago) again had no bad sectors after reformat anymore and its health status is labeled as ok by HDTune Pro (the tool I use for drive diagnostic), but there is at least one part of the drive where the reading speed, this rime, becomes very slow. The part is at the position 48-54 GB on HDTune's drive map and the reading speed slows down there to 4-5 MB/s. The writing speed is fine over the entire drive.

Is there any way to fix this? Not to repair the damaged sector (that is pretty much impossible most of the time), but at least to mark the slower sections so that Windows won't try to write there.
The drives are still usable; the first which went bad had been stable for more than a year with constant usage, but this speed problem can become irritating when you hit the faulty sections.

Any ideas?

PS: Do NOT, under any circumstances, suggest buying replacement drives. Seriously, to buy some new ones it's something anyone can think of and does not need to ask expert advice for this - yet it seems to have become a common trope for some people, whenever they see the words "damaged drive", to reflexively suggest "buy a new one", regardless of the actual inquiry.
I also happen to have replacements and I'm not going to keep any important data on the faulty drives anymore. Everything which will go on them from now on will be expendable. It is just that I'm reluctant to completely let go of two drives which could still be used for a long time.
The first time I experienced bad sectors on a drive (a 3'5 drive in an external enclosure), the respective drive was still used intensively for more than 20 months, while the number of bad sectors remained stable. And, in the end, I gave up on it not because it failed, but because I shifted to smaller 2'5 drives.
Similarily, one of the current two Samsung G2s with bad sectors is still in use after more than 18 months and no new bad sectors appeared.
It's just I would like to know whether this speed problem in certain small sectors can be worked around somehow.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 12:25 pm

Format the drive and uncheck the "quick format" box, or open a command prompt and type "chkdsk e: /r" (replacing e: with the letter of your external drive). Either of those will mark bad sectors, but will take a while.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 12:26 pm

Bad sectors and slow performance imo is a dead drive. more sectors and or data loss is *guaranteed to occur* .. use at your own risk and consider any data on the drives as expendable in the next 5 minutes to the next 5 months until one day it is no longer recognized by gparted.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 12:41 pm

bthylafh wrote:Format the drive and uncheck the "quick format" box, or open a command prompt and type "chkdsk e: /r" (replacing e: with the letter of your external drive). Either of those will mark bad sectors, but will take a while.


Tried that, but it did not work (long format from Windows).

Bad sectors and slow performance imo is a dead drive. more sectors and or data loss is *guaranteed to occur* .. use at your own risk and consider any data on the drives as expendable in the next 5 minutes to the next 5 months until one day it is no longer recognized by gparted.


It seems some people just can't refrain themselves.
What part from the statements that I have been using drives with bad sectors up to 18-24 months, with no data loss, no failure and no more bad sectors and all data on them is going to be expandable anyway do you fail to understand?
To a certain point, this reflex is understandable, having in mind the number of people which show up in such forums thrown into despair after loss of data, but I think that what I specified above (that the respective drives are going to be reserved for "junk" usage only and they - at least one of them - had been perfectly stable for a very long time) should get the point across.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 12:59 pm

Noldor wrote:
bthylafh wrote:Format the drive and uncheck the "quick format" box, or open a command prompt and type "chkdsk e: /r" (replacing e: with the letter of your external drive). Either of those will mark bad sectors, but will take a while.


Tried that, but it did not work (long format from Windows).


Try the chkdsk, then, because I'm out of other ideas.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 1:19 pm

Noldor wrote:
bthylafh wrote:Format the drive and uncheck the "quick format" box, or open a command prompt and type "chkdsk e: /r" (replacing e: with the letter of your external drive). Either of those will mark bad sectors, but will take a while.


Tried that, but it did not work (long format from Windows).

Bad sectors and slow performance imo is a dead drive. more sectors and or data loss is *guaranteed to occur* .. use at your own risk and consider any data on the drives as expendable in the next 5 minutes to the next 5 months until one day it is no longer recognized by gparted.


It seems some people just can't refrain themselves.
What part from the statements that I have been using drives with bad sectors up to 18-24 months, with no data loss, no failure and no more bad sectors and all data on them is going to be expandable anyway do you fail to understand?
To a certain point, this reflex is understandable, having in mind the number of people which show up in such forums thrown into despair after loss of data, but I think that what I specified above (that the respective drives are going to be reserved for "junk" usage only and they - at least one of them - had been perfectly stable for a very long time) should get the point across.


You asked and you received. if you do not like the answer do not ask.

slow portions of the drive can only means 2 things :
1-the drives actuator arm is bad. this means the drive will literally stop working at some point and all data is lost.
2-the media has lost or is losing its ability to hold a magnetic pole and is to weak to track with the head. again, this *WILL* spread and again mass data loss.

since you were rude.. done with thread.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 1:58 pm

If you had a drive that continued to work for many months after developing hundreds of bad sectors, congratulations -- you got very lucky.

In my experience, drives that develop more than a small number of new bad sectors (where "small number" is more like a dozen, NOT hundreds) tend to die within a few weeks or months. There's a physical reason for this: new persistent bad sectors (ones that don't go away when rewritten) typically indicate that there's been a minor head crash, possibly from the drive getting bumped while it was spinning. The head crash causes a microscopic nick in the magnetic coating of the platter. The debris from this then floats around inside the drive causing additional head crashes, and the bad sectors multiply.

Been there, done that. I used to try and keep using marginal drives too, for non-critical data. I think the most I ever got out of one was about 6 months, before it degraded to the point where it became completely unusable. Most died within a couple of weeks.

If a full format didn't mark the sectors out, then the drive itself is still reporting that the sectors are good, but is having a hard time accessing them. The slow access is due to retries being done by the drive firmware to recover the data. If you're dead set on continuing to use these drives, what you'll need to do is whenever you notice a particular file that is accessing very slow, rename the file, then copy the contents back to the original file name. DO NOT delete the original file after making the copy; just move it to a folder called "Bad Files" or something like that. In effect, you're manually marking out the marginal sectors.

You will need to keep doing this every time new marginal sectors show up (and they likely will, for reasons indicated in the first paragraph above). You will probably also lose files occasionally when the error is severe enough to overwhelm the drive's retry and error correction capabilities. And if the marginal sectors happen to hit file system meta-data (directories, MFT, etc.) instead of user data you're pretty much screwed.

IMO unless you don't place any value on your own time it is not worth the effort. Yes, that's your own judgement call to make; but getting annoyed at people here for questioning your decision to keep using these drives is like going on a car forum, posting that you've got an old beater car with a dead transmission, oil leaks, no brakes, rust holes in the floor pan, and bald tires; then getting bent out of shape when people suggest that maybe it is time to have it towed to the junkyard. "Why would I want to junk this car? The engine still starts when I turn the ignition key!"
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 2:11 pm

You asked and you received. if you do not like the answer do not ask.


I asked for an orange. You served me a banana.

the media has lost or is losing its ability to hold a magnetic pole and is to weak to track with the head


Possible.

again, this *WILL* spread and again mass data loss.


This is factually false. The drive which, according to you, was supposed to die is still alive and kicking after two years since the first bad sectors appeared (something which I specified from the very beginning). Yes, it could fail. So could any brand new drive after 2 years of usage.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 2:43 pm

just brew it! wrote:If you had a drive that continued to work for many months after developing hundreds of bad sectors, congratulations -- you got very lucky.

In my experience, drives that develop more than a small number of new bad sectors (where "small number" is more like a dozen, NOT hundreds) tend to die within a few weeks or months. There's a physical reason for this: new persistent bad sectors (ones that don't go away when rewritten) typically indicate that there's been a minor head crash, possibly from the drive getting bumped while it was spinning. The head crash causes a microscopic nick in the magnetic coating of the platter. The debris from this then floats around inside the drive causing additional head crashes, and the bad sectors multiply.

Been there, done that. I used to try and keep using marginal drives too, for non-critical data. I think the most I ever got out of one was about 6 months, before it degraded to the point where it became completely unusable. Most died within a couple of weeks.

If a full format didn't mark the sectors out, then the drive itself is still reporting that the sectors are good, but is having a hard time accessing them. The slow access is due to retries being done by the drive firmware to recover the data. If you're dead set on continuing to use these drives, what you'll need to do is whenever you notice a particular file that is accessing very slow, rename the file, then copy the contents back to the original file name. DO NOT delete the original file after making the copy; just move it to a folder called "Bad Files" or something like that. In effect, you're manually marking out the marginal sectors.

You will need to keep doing this every time new marginal sectors show up (and they likely will, for reasons indicated in the first paragraph above). You will probably also lose files occasionally when the error is severe enough to overwhelm the drive's retry and error correction capabilities. And if the marginal sectors happen to hit file system meta-data (directories, MFT, etc.) instead of user data you're pretty much screwed.

IMO unless you don't place any value on your own time it is not worth the effort. Yes, that's your own judgement call to make; but getting annoyed at people here for questioning your decision to keep using these drives is like going on a car forum, posting that you've got an old beater car with a dead transmission, oil leaks, no brakes, rust holes in the floor pan, and bald tires; then getting bent out of shape when people suggest that maybe it is time to have it towed to the junkyard. "Why would I want to junk this car? The engine still starts when I turn the ignition key!"


Mr. Just Brew It, thank you very much for your reply. This is the kind which I wanted and was hoping for.

but getting annoyed at people here for questioning your decision to keep using these drives is like going on a car forum, posting that you've got an old beater car with a dead transmission, oil leaks, no brakes, rust holes in the floor pan, and bald tires; then getting bent out of shape when people suggest that maybe it is time to have it towed to the junkyard


That is true, but I anticipated that I will be advised to "tow it to the junkyard" so to speak and I specified from the very beginning that I will not discuss this matter. Simply because I do not see the point in getting into 1000 arguments about "junking the car", sidetracking the issue I asked about in the process.
Basically, I did not get annoyed just because Maxxcool told me the drives are going to die. I got annoyed because Maxxcool did that despite that I asked everyone not to approach this matter, as I specified I was perfectly aware of it myself.

If you had a drive that continued to work for many months after developing hundreds of bad sectors, congratulations -- you got very lucky.


Two drives, actually. Basically, I had only 2 drives which developed bad sectors - both continued to work for at least 18 months after that. The most recent one (a Samsung G2 Portable) is still working, two years after it had developed the first bad sectors. It had quite a lot of them - I don't recall exactly how many because it's a long time since then, but there were at least several hundreds, perhaps more.
I have no suffered any data loss from it. When a second one went bad a week ago, I scanned all my externals and internals. The faulty Samsung G2 was pretty much in the same state as it was 2 years ago. HD Tune Pro (the tool I used for diagnostic) found 18 unstable sectors (approximate the same number as then) and ONE new bad sector, which I'm not even sure it wasn't there from 2 years ago.

The first drive I had which went bad was a 3'5 internal Samsung of 500 GB in an external enclosure. I think it developed at a certain moment at least 100 bad sectors. I checked it with HDD Regenerator (I did not have HD Tune Pro), don't recall if I also reformatted, and kept using that drive for about one year and half. Again, I experienced no data loss and I think there were no new bad sectors (don't recall this very well). I gave up on it only because I shifted to 2'5 drives, but I think it might still work (I still have it somewhere).
Over the mentioned time period, of 18-24 months, both those drives have been subjected to the kind of usage which would make even even a new drive scream. Basically, I was in a "if they are going to fail, I'm gonna turn them to dust first" kind of mood. They withstood all that abuse with no further "scratches", so to speak.
In these kind of circumstances, I think you can understand why I am reluctant to let them go.

Maybe Samsung models are just very resilient? :P
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 2:49 pm

Noldor wrote:
You asked and you received. if you do not like the answer do not ask.


I asked for an orange. You served me a banana.


You asked for advice on a website called "The Tech Report" - most of the people who post on this forum are computer people, or are looking for advice from computer people. And the advice you received was entirely accurate and appropriate. Your childish reaction to it was not.

again, this *WILL* spread and again mass data loss.


This is factually false. The drive which, according to you, was supposed to die is still alive and kicking after two years since the first bad sectors appeared (something which I specified from the very beginning). Yes, it could fail. So could any brand new drive after 2 years of usage.


The drive might last another two years; or it might fail today. That's the point. While it's technically possible that a brand new drive might fail after two years of use, the odds of failure are much, much higher for your drive that has already shown a problem. That is why people are advising you to replace the drive, or to at least not use it for anything important. When drives start showing the types of issues you are describing, they typically do not live long afterwards. Sure, that isn't always the case - but it's the case often enough that people who know what they're talking about tend to recommend replacement.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 3:13 pm

You asked for advice on a website called "The Tech Report" - most of the people who post on this forum are computer people, or are looking for advice from computer people. And the advice you received was entirely accurate and appropriate. Your childish reaction to it was not.


Advice does not have to be just entirely accurate or appropriate. It also has to actually adress the matter one inquired about.
If one asks "how to improve the performances of my failing drive", to answer "your drive is going to die and use it at your own risk" is not accurate, nor appropriate. It's irellevant.

The drive might last another two years; or it might fail today. That's the point. While it's technically possible that a brand new drive might fail after two years of use, the odds of failure are much, much higher for your drive that has already shown a problem.


Yes, that was the point, which is not "accurate and appropiate", because I have not asked about the odds of failure of a drive with bad sectors.

That is why people are advising you to replace the drive, or to at least not use it for anything important.


Which I already done and I have said so in the first post. Let me describe it in more simple terms how this dialogue went:

Me: I want to know if I can make a failing drive work better. I have already replaced it and I will not use the failing drive for anything important.
Maxxcool: The drive is going to die, use it at your own risk.
Me: That was not the point.
Maxxcool: You are rude.
Cphite: Your reaction is childish. You should listen to people who tell to replace the drive, or to at least not use it for anything important.

Yes, I asked for advice on a website called "The Tech Report". Just Brew It and Bthylafh provided such. The above exchange, though, I'm not going to call it trolling, but such kind of unsolicited digressions do sound like it and are quite frustrating.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 3:23 pm

just brew it! wrote:If you had a drive that continued to work for many months after developing hundreds of bad sectors, congratulations -- you got very lucky.

In my experience, drives that develop more than a small number of new bad sectors (where "small number" is more like a dozen, NOT hundreds) tend to die within a few weeks or months. There's a physical reason for this: new persistent bad sectors (ones that don't go away when rewritten) typically indicate that there's been a minor head crash, possibly from the drive getting bumped while it was spinning. The head crash causes a microscopic nick in the magnetic coating of the platter. The debris from this then floats around inside the drive causing additional head crashes, and the bad sectors multiply.



One question: could those have been soft bad sectors if my respective faulty drives kept working? On HD Tune pro, all show the same. In general, how does one know whether the bad sectors are hard or soft?
I think that might have been the case, since physical bad sectors can't actually be mapped out by conventional diagnostic/repair utilities.

There's a physical reason for this: new persistent bad sectors (ones that don't go away when rewritten) typically indicate that there's been a minor head crash, possibly from the drive getting bumped while it was spinning


Well, the bad sectors DID went away when rewritten. It's just that, after that, the drives were left with some parts where the speed slows down considerably: in one drive, ONLY the write speed decreases, while the read speed is good over the entire drive, in the second drive, the write speed is perfectly fine, but the read speed decreased over one section of about 6 GB.
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Re: Damaged external drive partially slow after reformat

Postposted on Mon Jan 06, 2014 9:16 pm

Noldor wrote:In general, how does one know whether the bad sectors are hard or soft?


A soft failure is when a sector fails to read but after writing new data to it, the sector reads just fine. A hard failure is one where a sector read fails and writing new data to fails to correct this read error. In the latter case, the drive will remap the failed sectors to other areas of the disk until it runs out of sectors set aside for re-mapping.

Noldor wrote: Well, the bad sectors DID went away when rewritten. It's just that, after that, the drives were left with some parts where the speed slows down considerably: in one drive, ONLY the write speed decreases, while the read speed is good over the entire drive, in the second drive, the write speed is perfectly fine, but the read speed decreased over one section of about 6 GB.

[

If all the bad sectors went away, that means the drive re-mapped them to spare space set aside for this purpose. It may actually be this re-mapping that is slowing down access. I don't know how these particular drives set asside spare space, but consider this example scenario (constructed to illustrate the point). Assume your bad sectors are on the outer edge of the drive and they are in a line such they cross multiple tracks with a single bad sector per track. Now also assume that the bads sectors have been remapped to a spare area at the inside of the disk. Each time you try and read the area with bad sectors it will read up to the point of the bad sector, then have to move the head all the way to the inside of the disk. Further assume that as it moves the heads in, the remapped sector has passed the heads and the drive now has to wait an entire rotation to read the sector. Once it has read the sector, it has to move the heads all the way back out to the outer section and will have missed the next sector after the bad spot, again waiting an entire rotation of the disk to resume the read.

If you have a rotational latency of 8ms and a full stroke seek latency of 18ms, then you are looking at 52ms of latency for every bad sector. 100 bad sectors in that chunk of 6MB would mean that it takes over 5.2s just to read that data, or about 1.15MB/s which is two orders of magnitude slower than a reasonable 500GB drive.

As I said, I constructed the worst possible case I could think of for the example but I wanted to give a good illustration of why sector remapping would make an otherwise fully function drive appear very slow. I don't have a good reason why your would see asymmetry in read and write performance though.

--SS
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