[kwlug-disc] Media errors on a USB disk

Khalid Baheyeldin kb at 2bits.com
Sat Oct 23 21:52:56 EDT 2010


On Sat, Oct 23, 2010 at 9:41 PM, unsolicited <unsolicited at swiz.ca> wrote:

> Khalid Baheyeldin wrote, On 10/23/2010 9:14 PM:
>
>  So, here is an update.
>>
>> I ran the e2fsck -c -y on the the disk (1TB), still in its USB enclosure.
>>
>> One thing I noticed is that it complained about the bad blocks inode being
>> shared by another file. Should I be concerned about this? Or has it been
>> fixed by fsck?
>>
>> Also, it took a long time. I know I can take the disk out of the enclosure
>> (with some tinkering, this USB enclosure is not designed to be opened),
>> but
>> I have reasons not to for the time being.
>>
>
> Warranty, or it's a client's, presumably.
>

No, neither.

Basically, there is no spare PC in a convenient location with power and
network
connection to eviscerate and connect the drive to.


> None of your messages to date indicate you mistrust the data that's there,
> so I'll leave that branch of this thread. Mind you, Charles' advice about
> taking an image (now?), resonates. Presumably a raw image. Thus, if it's a
> client's, you may be protecting your backside by taking one. (Hopefully you
> don't have to buy another USB drive just to back up this one. See 'irony.')
>

The disks are used for backup, and they are not the only disks that have
that. I do backups daily to 2 separate disks. These ones are the higher
capacity (the other is only 500GB), and they are the fixed disks (the others
are removable and go off site on a rotation).

So all the data on these disks are replicated elsewhere and hence
replaceable, with some moderate effort.

The decision here is to detect whether these disks are no good for future
backups, can they be trusted, what caused them to go bad (is it really
physical platter problem, or just USB connection, or what exactly).

One of them has been on constantly for maybe 1.5 years. The other was on for
part of that.

 Hopefully this is the only USB device you have hooked up at the moment, at
> least on that channel.


When running fsck, this was the only active device on USB on that machine.
There is another on some other USB port, but it was not doing anything.


> Any change if you use a different usb port?


Not going to try it again for 14 hours.


> The AC adapter is plugged in to it?


Yes, it is powered by a separate adapter.


> Have you noticed any difference between a 'powered' usb port and a
> non-powered one?
>

Don't use any non-powered ones at the moment.


> If warranty is the issue ... well ... how 'bad' does a drive have to be
> (per your manufacturer) before it is replaceable? Perhaps worth finding out?
>

Not sure if they are under warranty or not. Need to lookup the receipts to
know.


> This thread does make me wonder ... are you dealing with file system
> corruption, or a disk going bad (let alone the usb interface "isn't ATA").
> If it's disk corruption, presumably file system corruption is not far
> behind, jeopardizing the files that are currently there and healthy, now.
> (You have a backup?) Could that be what you are now seeing? (Thus the inode
> issue, now?)
>

The errors came up the same with the same block numbers as before. So maybe
it is physical damage, but I can't rule out FS corruption either.

Someone who knows this stuff better can chime in.


> Since it's a USB drive and you're reluctant to extract it, I'm guessing the
> manufacturer intended it to only ever be a USB drive. In that case ... might
> they have a diagnostic program that does run over USB?


Even if I can find a Windows booted PC, will the diagnostics still work on
an ext3 filesystem?
-- 
Khalid M. Baheyeldin
2bits.com, Inc.
http://2bits.com
Drupal optimization, development, customization and consulting.
Simplicity is prerequisite for reliability. --  Edsger W.Dijkstra
Simplicity is the ultimate sophistication. --   Leonardo da Vinci
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