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Compact Drive PD70x - I lost data?

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Matt Cham

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I've had nothing but VERY GOOD experience with the
PD70x. But recently I lost data when trying to
use it as an external hard drive to store video files.

I copied the video files via my PC and USB into
a PD70x folder that already existed from a prior
successful CF card transfer. The folder was
called CARD0013.UHS (standard PD70x folder
naming scheme).

I then continue to use the PD70x normally,
backing up many CF cards successfully.

When I hook up the PD70x to my PC via
USB, I notice that there are now two
CARD0012.UHS folders, both containing
the same image files that they are supposed to
contain. However, folder CARD0013.UHS
is now missing and so are all its contents.

I understand that WinXP does not normally
allow two files or folders of the same name to
co-exist, but there they are: two CARD0012.UHS
folders!

I have been building PC's since 1991, so
I know my way around data recovery.
I used EasyRecovery Professional to extract
the lost files, and I recovered every missing
file from the PD70x. Whew!
According to EasyRecovery, my files
were located in the second CARD0012.UHS
folder. According to WinXP, the second
CARD0012.UHS folder has the same files
as the first CARD0012.UHS folder.

Anyone care to explain what happened here?

Just FYI, I have never had any error codes from the
PD70x or from my PC. I always "safely eject" USB
devices. I never had power outage or battery loss.
Everything has worked flawlessly. All CF transfers
to PD70x have been successful (over 90GB and
counting) since I bought it.

What was my mistake here?
a.) I copied non-photo files (AVI video files) into the PD70x?
b.) I copied into a existing folder within the PD70x?
c.) I copied files into the PD70x via USB?

--
Matt Cham

My Gallery: http://mattcham.fotopic.net/
 
Matt Cham said:
What was my mistake here?
a.) I copied non-photo files (AVI video files) into the PD70x?
Click to expand...
This is allowed. This should not be a problem (I did it too on mine).
Matt Cham said:
b.) I copied into a existing folder within the PD70x?
Click to expand...
It could be a little more risky, but technically speaking I'm not sure I could prove it.
Matt Cham said:
c.) I copied files into the PD70x via USB?
Click to expand...
This is standard practice.

Idea: Could have been a glitch in the transfer via USB (sometimes bad cables or interfaces badly designed can be the source).

Did you have the PD70X correctly powered from the outside? It's always better to use the external PS rather than only the batteries when you work from USB.

--
Yves Roumazeilles
http://www.roumazeilles.net/news/en/wordpress/category/digital-photography/
KM Dynax 7D (Minolta forever, 'til the replacement)
 
Hi,

Have you tried a "dir x" for viewing short and long names of the folders?

Windows might have created a different short name for the folder, while the gizmo created such a short name the same as the long name of the folder Windows created, but without long name?

Hans-Jürgen
--
CARDSPEED - Card Readers and Memory Cards - http://www.hjreggel.net/cardspeed/
HD-Info - Harddisk Information - http://www.hjreggel.net/hdinfo/
 
Matt Cham said:
What was my mistake here?
a.) I copied non-photo files (AVI video files) into the PD70x?
b.) I copied into a existing folder within the PD70x?
c.) I copied files into the PD70x via USB?
Click to expand...
I think using the existing folder was no good idea.

I guess the CompactDrive just continued numbering the folders, not caring about any other existing files. During FAT (file allocation table) update obviously your files got lost because the manufacturer didn't consider that a user might copy files to this location by himself. This obviously is a bug.
Werner
 
Along these same lines...

I wonder what would happen if you format the HD in a PD70X/HD80, create then the first thing you do is to create a folder called CARD0002.UHS, put some data in it... and then went to use the PD70X as a PSD to copy a card... I suspect that the file would get overwritten or duplicated and/or the same senerio of the lost video files would occur. I think Werner is likely correct that the PD70X, probably doesn't look to see if the named folder already exists and it just writes anyway.
d70_europe said:
Matt Cham said:
What was my mistake here?
a.) I copied non-photo files (AVI video files) into the PD70x?
b.) I copied into a existing folder within the PD70x?
c.) I copied files into the PD70x via USB?
Click to expand...
I think using the existing folder was no good idea.
I guess the CompactDrive just continued numbering the folders, not
caring about any other existing files. During FAT (file allocation
table) update obviously your files got lost because the
manufacturer didn't consider that a user might copy files to this
location by himself. This obviously is a bug.
Werner
Click to expand...
 
I think you can rule out the pd70x itself. My guess is the file copy across the usb somehow corrupted some data on the drive. Each CF copied starts a new folder card0000.uhs, 01, 02... etc, if you create a folder after there are 5 (00-04) folders existing, say "myfiles" for example it will not create "05" but will continue with "06" with the next CF card download. Folders are named by total number of folders found on the drive.

In your case both "12" and "13" must have been clobbered in order for the next CF card downloaded to use "12" over. I'm guessing "13" didn't exist and you copied files into "12" and it went corrupt leaving the pdx controler to see only 11 folders on the drive.

What caused this? A bad spot on the drive to begin with maybe, using an extension usb cord maybe, using an external usb hub maybe... Or something external to the drive and usb interface like a power spike or another unrelated process trying to use the same spot in memory as the file transfer... And don't rule out this happening sometime after the data was already transfered and possibly accessed a time or two...

Glad to hear you recovered your data, from here I would clean off the drive and run some diagnostics that will mark any bad sectors so they can't be used in the future.

--
...Dennis
 
Glenn W. said:
Along these same lines...

I wonder what would happen if you format the HD in a PD70X/HD80,
create then the first thing you do is to create a folder called
CARD0002.UHS, put some data in it... and then went to use the PD70X
as a PSD to copy a card... I suspect that the file would get
overwritten or duplicated and/or the same senerio of the lost video
files would occur. I think Werner is likely correct that the PD70X,
probably doesn't look to see if the named folder already exists and
it just writes anyway.
Click to expand...
Good question, the hd/pdx gets it's naming from folder place holders as in my previous example. The 1st folder is place holder card0000 the second is card0001 and so on. In your example the user created folder card0002 that is place holder 0000 and the next CF card folder created is card0001. That puts us back to the point of your post when we get to the next place holder which would be folder name card0002 which already exists. I don't know for sure but I think you would throw an error code #9 or #15 dealing with folder structure.

Without duplicating system generated folder names and having that folder fall in the right place this could never be duplicated. In the OP's case I can't see this happening unless he left out some facts.
--
...Dennis
 
Interesting to see that you can follow 2 speculations with a very conclusive statement.
d70_europe said:
I think using the existing folder was no good idea.

I guess the CompactDrive just continued numbering the folders..

This obviously is a bug.
Werner
Click to expand...
 
The PD70X/HD80 looks for the first available folder "slot", starting from card0000 (by default). It does not overwrite pre-existing folders.

You can override the folder naming convention to a certain extent, but it works in the same way - lookng for the next available slot.

P.
 
I'm inclined to agree Dennis. The folder number the PD70X makes is based on the position of the first free FAT entry, so if 12 was seen to be free then it can't have been updated after the files were written. Maybe this was due to a hardware fault, more likely that the disk wan't correctly dismounted after copying the files from the PC.

"Pulling the plug" on any USB drive after writing is likely to cause corruption, with a FAT32 drive it's almost guaranteed.

--
John Bean

PAW 2006 Week 19:



Iindex page: http://waterfoot.smugmug.com
Latest walkabout (4 April): http://waterfoot.smugmug.com/gallery/1348582
 
Then do my suggestion copying a second memory copy , or change the procedure where the name of the original folder created after format is card0001, rather then card0002, etc... It should be easy to test if this is going to cause a problem.

The ohter thing that should be realtively easy to test for, that may have caused a issue... Format the drive, copy a card, then use PC to add some new data to the card0000.uhs folder then go and do another card copy...

If both of those tests fail to re-produce the original issue of lost data, then it would seem it's some much more obsure issue that caused it.
5D DjD said:
Good question, the hd/pdx gets it's naming from folder place
holders as in my previous example. The 1st folder is place holder
card0000 the second is card0001 and so on. In your example the
user created folder card0002 that is place holder 0000 and the next
CF card folder created is card0001. That puts us back to the point
of your post when we get to the next place holder which would be
folder name card0002 which already exists. I don't know for sure
but I think you would throw an error code #9 or #15 dealing with
folder structure.

Without duplicating system generated folder names and having that
folder fall in the right place this could never be duplicated. In
the OP's case I can't see this happening unless he left out some
facts.
--
...Dennis
Click to expand...
 
I'm not a expert by any means in FAT32 or any file system. However, I would hope that your statment is not accurate. :) Yes there may be some corruption of data in the file that was being transfered at the time of the disconnect, but I would not expect the FAT system to get corrupt to the extent that it starts making data disapear, or at least I hope not. I've done this a few times on purpose, and I've never exerianced anything like that with my PSDs. But then I've never done the exact same thing, where adding a bunch of data to pre-existing folder in the course of this kind of test.

I hope there is some expert out there that can say definitively what could/should, or would happen... I use my PSD all the time as a external drive, and if this is a issue that can happen related to a premature disconnect, etc... and FAT filesystem itself is volnerable to this sort of thing, I deffintely want to know about it.
John Bean (UK) said:
"Pulling the plug" on any USB drive after writing is likely to
cause corruption, with a FAT32 drive it's almost guaranteed.
Click to expand...
 
Yves Roumazeilles said:
Idea: Could have been a glitch in the transfer via USB (sometimes
bad cables or interfaces badly designed can be the source).
Did you have the PD70X correctly powered from the outside? It's
always better to use the external PS rather than only the batteries
when you work from USB.
Click to expand...
I know the USB cable is good because I never
had a problem after over many GB of CF card
transfers from PD70x to my PC.

My PD70x is always powered via electrical
outlet (AC adapter) during USB-to-PC usage.

Like I said, I've never had an error message.

--
Matt Cham

My Gallery: http://mattcham.fotopic.net/
 
Hans-Jürgen Reggel said:
Have you tried a "dir x" for viewing short and long names of the
folders?

Windows might have created a different short name for the folder,
while the gizmo created such a short name the same as the long name
of the folder Windows created, but without long name?
Click to expand...
The folders are all short names. I never created
any long names (over 8 characters + 3 extension),
and neither does PD70x.

--
Matt Cham

My Gallery: http://mattcham.fotopic.net/
 
There's cached data specifically for FAT32 (like free space count for example) stored in the boot sector that doesn't get written until the drive gets dismounted - unless you explicitely set the "fast removal" policy which I do. In addition to the special FAT32 caching other data may be lost in lazy caching if the plug is pulled, often resulting in root directory information being out of date if data has been added to a root folder as in this case.

More than enough concern to justify saying that "pulling the plug" on a FAT32 USB volume as A Very Bad Idea, rather than just A Bad Idea as it is for any USB disk.

--
John Bean

PAW 2006 Week 19:



Iindex page: http://waterfoot.smugmug.com
Latest walkabout (4 April): http://waterfoot.smugmug.com/gallery/1348582
 
5D DjD said:
I don't know for sure
but I think you would throw an error code #9 or #15 dealing with
folder structure.

Without duplicating system generated folder names and having that
folder fall in the right place this could never be duplicated. In
the OP's case I can't see this happening unless he left out some
facts.
Click to expand...
No facts were left out. PD70x never gave an error message
even after transfering a few more CF cards, all of which
were successful (smiley face which check mark).

--
Matt Cham

My Gallery: http://mattcham.fotopic.net/
 
Hi Glenn,

It is good practice to unmount devices properly.

However, FAT is supposed to keep track of the status. From fatgen103.doc:

"Bit ClnShutBitMask – If bit is 1, volume is “clean”. If bit is 0, volume is “dirty”. This indicates that the file system driver did not Dismount the volume properly the last time it had the volume mounted. It would be a good idea to run a Chkdsk/Scandisk disk repair utility on it, because it may be damaged."

This means that the operating system should recognize potential problems and avoid damage by performing a scandisk.

As stated above, I would double-check for problems with short and long directory names. As a side note: I would never bet a single cent on the reliability of PDxx FAT implementations.

Hans-Jürgen
--
CARDSPEED - Card Readers and Memory Cards - http://www.hjreggel.net/cardspeed/
HD-Info - Harddisk Information - http://www.hjreggel.net/hdinfo/
 
Forgot to add: this isn't a problem with FAT32 as such, it's a problem with Microsoft's default handling of FAT32 in an effort to speed up access to large FAT32 volumes in XP by minimising the number of seeks to the boot sector to keep the data up to date.

--
John Bean

PAW 2006 Week 19:



Iindex page: http://waterfoot.smugmug.com
Latest walkabout (4 April): http://waterfoot.smugmug.com/gallery/1348582
 
5D DjD said:
I think you can rule out the pd70x itself. My guess is the file
copy across the usb somehow corrupted some data on the drive. Each
CF copied starts a new folder card0000.uhs, 01, 02... etc, if you
create a folder after there are 5 (00-04) folders existing, say
"myfiles" for example it will not create "05" but will continue
with "06" with the next CF card download. Folders are named by
total number of folders found on the drive.

In your case both "12" and "13" must have been clobbered in order
for the next CF card downloaded to use "12" over. I'm guessing
"13" didn't exist and you copied files into "12" and it went
corrupt leaving the pdx controler to see only 11 folders on the
drive.
Click to expand...
To clarify, I copied the video files into folder named "13" and
not the folder named "12".

The fact that I successfully recovered all my video files
in the "now missing" folder "13" despite several
recent CF-to-PD70x transfers (> 6 GB of additional CF data)
tells me that the PD70x did not actually overwrite folder "13".

PD70x knew that there was data after folder "12",
and skipped to folder "14" when creating a new folder
for the next CF card transfer. No problem there.

However, I cannot explain how a second folder "12" could be
created. More specifically, how folder "13" could have
been renamed as a second folder "12". WinXP cannot
cannot create two folders of the exact same name
within a root directory.

Could the PD70x have renamed my folder "13" into a
second folder "12" ?

I know the PD70x is incapable of deleting individual folders.
But can the PD70x rename individual folders to suit its
firmware logic while at the same time not giving an error message?

I highly doubt this is a hard drive hardware problem
because I never get corrupted image files and this event
only happened as a result of my unique scenario outlined in
my original post.

--
Matt Cham

My Gallery: http://mattcham.fotopic.net/
 
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