HDD not recognized after changing drive Letter

By Windranger ·
I changed the drive letter of an external 2.5' HDD (from F to D).

Then for some reason I suddenly can't use the drive anymore.

Now when I plug it, the error message is on Win7 is "You need to format the disk in drive"
The error on Win XP is D:\ is not accessible

which is quite weird.

The drive is not used much, it never had surface problems, etc.
Of course I don't want to format it because I have some info there.

Any ideas about what the problem could be...?


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Reponse To Answer

by Cmd_Line_Dino In reply to no reserved drive letters ...

@Who Am I Really
I have two objections to your post.

Static electricity
You are exaggerating the dangers of static electricity.

Do you not think that the designers of the actual disk drives have not worked hard to resist static electricity.

Yes external drives will just fail. They are commodity products, mass produced, always seeking lowest cost to manufacture. Cooling is often marginal. Time and heat (added by dust) take their toll. Components weaken. One day the surge of power up becomes too much and a component fails.
These fail on power up have led to the debate between "never power off" and "power off when done"
Is static electricity the great destroyer of external drives. I don't think so.

Safely Remove is not needed
The requirement to use "safely remove" is incorrect old advice.
External drives, by default have write caching disabled.
Once a few seconds have passed after the last activity the drive can just be unplugged.

In order to see the setting...
In windows explorer right click the drive -> properties -> Hardware (tab) -> in the list select the disk and click Properties -> Change settings -> Policies (tab) -> and you will see...

Removal Policy
(*) Quick removal (default)
Disables write caching on the device and in Windows, but you can disconnect the device safely without using the Safely Remove Hardware notification icon.

This is the default even for external disks that are NTFS formatted

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Reponse To Answer

by OH Smeg In reply to no reserved drive letters ...

but you can disconnect the device safely without using the Safely Remove Hardware notification icon.

That is your mistake you Can Not Safely do what you are suggesting without running the risk of corrupting the Partition Tables on the HDD itself.

When you remove the plug all you are doing is removing the power and leaving the HDD to it's own devices to park it's Read Write Heads and stop immediately what ever it was doing. If it was performing a Write to the drive no power means that the Write is incomplete and possibly the Read Write Heads could have touched the Platters damaging the Heads and the platters in the process.

While you may get away with just pulling the USB Plug 99 times out of 100 it's going to eventually come and bite you on the Backside and trash your data which is what I think you'll find has happened here.


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Reponse To Answer

by Slayer_ In reply to no reserved drive letters ...

I'm fairly certain you cannot damage NTFS that way.
But Fat32 (which it seems flash drives are still formatted too), definitely could damage it.

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@ gechurch 4

by Cmd_Line_Dino In reply to HDD not recognized after ...

The point of my advice was to do some first-step basic trouble shooting.
Trying the disk on another computer would have been another first step.
Evaluate, diagnose, remediate.

What would you have advised ?

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Reponse To Answer

by gechurch In reply to @ gechurch 4

Sorry if I came across as snarky Cmd_Line_Dino. That wasn't my intention. I have a lot of respect for the people that give up their time to help out others on these forums, and I don't want to discourage you from doing so.

I did actually write another post about what I thought the issue was but it didn't save for some reason (happens to me sometimes... I think it's a problem with my laptop, it badly needs a reformat). As others have said, it is corruption; perhaps a physical fault, or perhaps from yanking the drive out without first safely removing it. Whatever the case Windows can clearly see the drive and recignizes it as being a hard drive, but it cannot make sense of the file system so offers to format it. A thorough chkdsk might fix the problem, or using a tool like TestDisk to repair the partition table might also do the trick.

I do need to point out that Safely Remove Hardware is still needed and it is dangerous advice to suggest otherwise. Sure, 99% of the time you will get away with doing it provided you wait 30 seconds after you *think* the computer has finished using it. That other 1% is the problem; that's where problems like the OP's come from. (Personally I'm lazy and yank my drives ut 90% of the time. I always safely removeh drives that have data I really care about though).

The reason you need to safely remove (even if you have optimised for quick removal turned on) is that the drive will often be accessed in the background. Anti-virus systems and poorly written shell extensions that don't close handles are the two worst offenders for this in my experience.

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@OH Smeg

by Cmd_Line_Dino In reply to HDD not recognized after ...

About using safely remove
So we should believe you rather than Microsoft ?
On there website MS CONTINUES to say it's not needed.
I will go with MS considering their decades of experience dealing with a vast universe of hardware.
But of course, as MS says, don't pull the cable while there is activity.

And why do you and others here keep saying the partition tables will be damaged.
First, for the vast majority of systems it's partition table (singular).
Second, for those systems it's a single 512 byte sector on the disk which is NEVER changed UNLESS you are reconfiguring the partitions on the disk.
Just because it's sector 0 is that why you think it's going to be changed/corrupted ?

About power being abruptly removed from an active hard disk
Disk drives are DESIGNED TO DEAL with the unexpected loss of power.
They immediately park the heads in the landing zone. Some use the rotating spindle to generate power to do the last activity and parking.
Think about how each day around the world hundreds of thousands of systems either abruptly lose power or are just powered off with no use of system shutdown. And for the vast vast majority nothing happens.

And about USB (AGAIN)
Here too, USB is designed for plug/unplug with the power on.
And here is a tidbit. In XP doing safely remove would drop the USB power.
Starting with Vista safely remove no longer drops the USB power.
Perhaps an evil MS plot to destroy USB devices ... nah probably not.

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Reponse To Answer

by Slayer_ In reply to @OH Smeg

I don't even see the safely remove anymore.

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by HAL 9000 Moderator In reply to HDD not recognized after ...

Feel free to believe what you want to it personally doesn't worry me in the slightest.

I will however mention that I make a lot of money by recovering lost data on external HDD that people have corrupted the Partition Table as you seem to prefer

I didn't say that it happens with SSD Drives or things with no movable parts but it most defiantly happens with mechanical HDD. I currently have a 2 TB Drive from a customer which is unreadable and they want their data back off it. Easy Money when the customer does stupid things. :^0


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More info

by Windranger In reply to HDD not recognized after ...

The HDD is SATA; I can't rename it back because the computer doesn't see it, even in Disk Management. There's no drive assigned with letter D.
Of course, any HDD can fail, but this problem coincided with changing the drive letter, so it's quite a low probability that the cause is different.

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Reponse To Answer

by Slayer_ In reply to More info

It doesn't show anything, not even unallocated space?

Sounds more like the drive is dead.

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