UM46 - "ghost files" - physically impossible?

The place for questions about shooting with Blackmagic Cameras.
  • Author
  • Message
Offline

Emilian Dechev

  • Posts: 222
  • Joined: Fri Jan 15, 2016 5:09 pm

UM46 - "ghost files" - physically impossible?

PostThu Aug 10, 2017 6:12 pm

Hi all,

After a shoot today with a Ursa Mini 4.6K (latest update), I succesfully downloaded 1 Lexar 3600X 256GB card. Sadly, I could not download the 2nd Lexar 3600X, also 256GB.

I know that such things happen frequently, but today's case is most peculiar. What happened is OUT of technical explanation, OUT of the law of physics, if you will...

So let me try to explain:

1.
I put the 1st Lexar card and download it to a MAC laptop. Lexar USB 3.0 reader. All 65 files are succesfully copied. They are numbered from 001 to 065 so there is no mistake about that. Their full size is of 238GB.

2.
After that I swapped to the 2nd card and continued to shoot normally...
During the shoot, I reviewed the files from the 2nd card inside the camera - playback was alright.

3.
Then I put the 2nd Lexar card. And here is the thing - the MAC OS shows, that the files inside the 2nd card are IDENTICAL to the files, that were copied from the 1st card, 2 hours ago. What ???

It seems, as though the MAC OS sees the same card. That is physically impossible, since there is no connection between the 2 cards and no file transfer was initiated with the 2nd card.

Of course, these "phantom files" were corrupt. They cannot be opened, since they cannot even exist in the 2nd card. They exist only in the 1st card, but the OS sees them inside the 2nd card.

All of the file names and sizes match.

Tried to read on Windows - same thing.

Tried to read back in camera - it cant detect any files.

I am shooting with this camera for more than 1 year now and I have downloaded hundreds of cards. This is a first... and I looked very terrible, trying to explain to my client, a "ghost files" theory suited for the "X-files" TV show...
Offline

Tim Schumann

Blackmagic Design

  • Posts: 194
  • Joined: Tue Oct 23, 2012 6:21 am

Re: UM46 - "ghost files" - physically impossible?

PostThu Aug 10, 2017 7:45 pm

We have heard reports of similar things happening a number of times now. It looks to be related to an issue with the Lexar CR1 and CR2 card readers on Mac. This is a known issue that we have been able to reproduce and have reported to Lexar.

It happens when you do not eject your card before removing it.

There are other threads on here where people have reported similar issues. In most cases customers are reporting it with Lexar CFast cards but we have been able to reproduce it on other brands of card as well using the same reader. We were only able to reproduce it when the card has not been ejected before removing it from the reader.
Offline

Florian Duning

  • Posts: 43
  • Joined: Wed May 11, 2016 10:41 am

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 12:11 am

Hi,

Tim is correct. This is what happens when you only remove the card without unmounting it. The comouter thinks it is still connected and corrupts the files system when you insert a different card.

The footage on your card can be restored if you havn't tinkered around with it in any way! I have found, that "Data Rescue 4" can reliably recover the files in these cases without issues.
BUT it fails to recover anything if you try to fix the file system with the osx disk utility before. So, DO not try to recreate the file system or rewrite the partition table stuff and only use data rescue 4 to read the corrupted media without altering its structure.

Best regards,

Florian - Not affiliated with any recovery software company.
Offline

Emilian Dechev

  • Posts: 222
  • Joined: Fri Jan 15, 2016 5:09 pm

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 12:42 am

Florian, Tim,
Thanks for the helpful info! Will share thr results.
P.S. (I hate mac os)
Offline
User avatar

Jamie LeJeune

  • Posts: 690
  • Joined: Tue Feb 26, 2013 4:33 am
  • Location: San Francisco

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 2:57 am

Yikes! I use that exact Lexar Cfast reader with Lexar. Luckily, I've been using the app Hedge for my offloads as it automatically unmounts the card when the offload is complete.
www.incafilms.com
http://www.imdb.com/name/nm4601572/
Offline

Florian Duning

  • Posts: 43
  • Joined: Wed May 11, 2016 10:41 am

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 11:34 am

I also use the lexar card reader. It is perfectly usable and has never let me down. There is just one thing you must not **** up: Eject the previous card!

My workflow is: Eject card, remove the card and no new card goes in until the card reader was disconnected and reconnected to ensure, that the system is 100% aware, that the previous card is not connected anymore!

Make a red warning label on the card reader to remind you. Just see it as a "pre card connect checklist" :D
Offline

Emilian Dechev

  • Posts: 222
  • Joined: Fri Jan 15, 2016 5:09 pm

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 12:58 pm

Tried both data rescue and lexar rescue - could not restore the files. A reshoot seems the best option now.

I will never allow a mac to be used for loading on my set.
Offline
User avatar

Robert Niessner

  • Posts: 1200
  • Joined: Thu Feb 21, 2013 9:51 am
  • Location: Graz, Austria

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 1:57 pm

Emilian Dechev wrote:I will never allow a mac to be used for loading on my set.


Blaming the tools for user error?
Robert Niessner
LAUFBILDkommission
Graz / Austria
---------------------------------------------------------------------
Blackmagic Camera Blog (German):
http://laufbildkommission.wordpress.com

Read the blog in English via Google Translate:
http://tinyurl.com/pjf6a3m
Offline

Emilian Dechev

  • Posts: 222
  • Joined: Fri Jan 15, 2016 5:09 pm

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 5:22 pm

No blaming. It is a prevention method on a base of probability. Windows also gives errors, but these are fixable.

Someone on set, intentionally or not, could remove a card without ejecting.
Offline
User avatar

Stephen Press

  • Posts: 123
  • Joined: Fri Jan 20, 2017 9:38 pm
  • Location: New Zealand

Re: UM46 - "ghost files" - physically impossible?

PostFri Aug 11, 2017 10:00 pm

I thought it was just me. I've been on so many shoots where we have had endless issues with Mac and everyone swears they "just work" and they have never heard of any other problems, Macs always work always and I'm just jinxing it with all my PC fanboy negativity... :/
"A cameraman with out a camera is just a man"
Offline
User avatar

Dustin Svehlak

  • Posts: 317
  • Joined: Mon Oct 15, 2012 7:49 pm
  • Location: Austin, Texas

Re: UM46 - "ghost files" - physically impossible?

PostSat Aug 12, 2017 12:07 am

FWIW- I've run into strange issues with our Lexar branded card readers. The Codex branded ones are exorbitantly priced but very dependable and I've never had an issue with them. The Sandisk one seems fine but also feels brittle.
www.voltaicvideo.com
www.vimeo.com/voltaicvideo
Offline
User avatar

Robert Niessner

  • Posts: 1200
  • Joined: Thu Feb 21, 2013 9:51 am
  • Location: Graz, Austria

Re: UM46 - "ghost files" - physically impossible?

PostSat Aug 12, 2017 9:22 am

Stephen Press wrote:I thought it was just me. I've been on so many shoots where we have had endless issues with Mac and everyone swears they "just work" and they have never heard of any other problems, Macs always work always and I'm just jinxing it with all my PC fanboy negativity... :/


In my now several decades long experience with so called computer problems most of the time it was an 'error 99': Change user.

I just say it again: If you do it wrong like not ejecting a card the way it is supposed to be done, then don't blame the tools for your own failure to do it right. If you fuel your Diesel car with petrol, who is to blame?
Robert Niessner
LAUFBILDkommission
Graz / Austria
---------------------------------------------------------------------
Blackmagic Camera Blog (German):
http://laufbildkommission.wordpress.com

Read the blog in English via Google Translate:
http://tinyurl.com/pjf6a3m
Offline
User avatar

Stephen Press

  • Posts: 123
  • Joined: Fri Jan 20, 2017 9:38 pm
  • Location: New Zealand

Re: UM46 - "ghost files" - physically impossible?

PostSat Aug 12, 2017 11:43 am

First rule of Mac/Apple fandom... never blame the Mac. Apple are perfect. ;)
"A cameraman with out a camera is just a man"
Offline
User avatar

Robert Niessner

  • Posts: 1200
  • Joined: Thu Feb 21, 2013 9:51 am
  • Location: Graz, Austria

Re: UM46 - "ghost files" - physically impossible?

PostSat Aug 12, 2017 12:08 pm

Stephen Press wrote:First rule of Mac/Apple fandom... never blame the Mac. Apple are perfect. ;)


The only fallacy in yor reply: I have no Mac - I am PC only. And I am OS agnostic as I have used most of the common OSes in my life.
Robert Niessner
LAUFBILDkommission
Graz / Austria
---------------------------------------------------------------------
Blackmagic Camera Blog (German):
http://laufbildkommission.wordpress.com

Read the blog in English via Google Translate:
http://tinyurl.com/pjf6a3m
Offline
User avatar

Stephen Press

  • Posts: 123
  • Joined: Fri Jan 20, 2017 9:38 pm
  • Location: New Zealand

Re: UM46 - "ghost files" - physically impossible?

PostSat Aug 12, 2017 10:30 pm

No worries.
"A cameraman with out a camera is just a man"

Return to Cinematography

Who is online

Users browsing this forum: Denny Smith, Yahoo [Bot] and 10 guests