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Cut & Paste flac from one hd to another hd, Paranoid question, I admit.
tom_vienna_at
post Sep 7 2005, 12:53
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My 200 GB harddrive is full of flacs, and I want to cut & paste half of the flac-files to my second 150 GB harddrive... so to have some free space again on the 200 GB harddrive.

I would just cut & paste the files from one (internal) hd to the other (internal) other.

Here's where I am getting paranoid. Can the cut & paste do any harm to the files or alter them in any possible way? I don't think so, because after all - it is just digital bytes copied from one hd to the other.

Someone pls. confirm this, so I can overcome my paranoia.

Thank you,
Tom.


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M
post Sep 7 2005, 13:01
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Tom, you shouldn't have anything to worry about; a "cut and paste" is simply copying the binary information stored in each file to a new location. However, any time you are moving large amounts of data, there is always the possibility of something getting corrupted if your RAM is damaged, or if any of the physical sectors on your HD (either the source or destination) are damaged.

If you would like a little reassurance, the simplest method is to create an MD5 checksum for the files you will be moving. Then, rather than cut and paste, you could copy your files to the new location and leave the original files in place until you are able to verify those checksums against the newly copied files.

Hope this helps,
- M.
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kjoonlee
post Sep 7 2005, 13:15
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FLAC files have internal MD5 sums inside, and flac.exe has a --test or -t option for testing. You won't need an external checking app.

You can use flac.exe with a batch file to recursively check for errors.

some hints: http://www.hydrogenaudio.org/forums/index....showtopic=32944


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M
post Sep 7 2005, 13:31
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QUOTE (kjoonlee @ Sep 7 2005, 07:15 AM)
FLAC files have internal MD5 sums inside, and flac.exe has a --test or -t option for testing. You won't need an external checking app.
*


Hi kjoonlee. I'm aware of FLAC's internal verification routine, but there is a specific reason I suggested external MD5 checksums: tom_vienna_at did not specify whether or not he had tagged any of his FLAC files. The internal routine would suffice for verifying the audio data itself, but would give no indication of a corrupted tag, or any embedded metadata, providing the corruption did not affect the meta-indicators. An external MD5 routine calculates a checksum for the entire binary content of the file, metadata included.

- M.
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Synthetic Soul
post Sep 7 2005, 14:24
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I certainly wouldn't cut'n'paste on a paranoia level. I would copy'n'paste, verify, and then delete the source.

If copying large amounts of data I generally use XCOPY from the command line, using the /V switch to verify the copied files.

I would also either create an MD5 digest of the folders to do a compare, or use FLAC to verify each file, as well.

You could perform all actions from one batch file.

You know what they say: Just because you're paranoid, donít mean they're not after you.


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JohanDeBock
post Sep 7 2005, 14:55
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http://www.slavasoft.com/fsum/

do this in source dir:
fsum -jm -r *.flac > chk.txt

copy chk.txt to destination dir

do this in destination dir:
fsum -c chk.txt

This post has been edited by JohanDeBock: Sep 7 2005, 14:57


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Jens Rex
post Sep 7 2005, 15:21
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I think you're all way too paranoid. If you get data corruption by moving files around, you need to fix whatever is wrong with your computer, instead of working around it.

First step: Don't overclock.
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atici
post Sep 7 2005, 15:58
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Files get corrupted during copy sometimes. It is very rare but it really happens. I copied my 300gb music archive and there were a few files with checksum mismatch. The best approach is to just copy first (not cut) and verify the checksums afterwards and copy the files with mismatch again and then delete the originals. Quoting myself in a different thread:
QUOTE (atici @ Jun 10 2005, 11:55 PM)
I would suggest using a file comparison program like Beyond Compare for this purpose. After the transfer you can compare the MD5 checksums automatically. The two group of files do not have to be simultaneously accessible to the same computer. You can take a snapshot (including MD5 checksums) of a group of folders -> transfer the snapshot file -> compare the snapshot to another group of folders on another computer.
*
Have a look at the thread quote is taken: link -- it discusses a similar problem. If you decide to use Beyond Compare in the end make sure CRC verification is enabled.

This post has been edited by atici: Sep 7 2005, 16:16


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Defsac
post Sep 7 2005, 17:04
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It is certainly possible to get a false positive CRC32 result during an Ethernet transfer (if the chance of 1 bit being corrupted as a result of a false positive CRC32 result is 1 in a billion, transferring 8gb of files will generate 68 corrupted bits). In reality the chance of a false positive is much less than this, but it can happen. Transferring from hard drive to hard drive is a lot less prone to errors, but if you're really worried using the included MD5 hashes as mentioned will reveal whether the audio data is intact. I personally wouldn't be too concerned about metadata, although there's a whole bunch of tools which can compare the MD5 or SHA1 checksums of an entire file if you want to be sure. Microsoft's FCIV is one. It's possible to write a batch script for this tool to add the checksum of each of your files to an XML database, then another script to verify that the MD5 or SHA1 checksum of the files on the second hard drive match the values in the XML database. It's not a very user friendly tool to work with, however.

Edit: Maths isn't my strong point at 2AM. wink.gif

This post has been edited by Defsac: Sep 7 2005, 17:21
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Martin H
post Sep 8 2005, 03:24
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FLACTester can test a whole tree of FLAC files for errors and generate a report. There's no install, it's just a single exe file. It works just like flac.exe's test function -t(and flac.exe's decode function -d, exept no output file is written). The decoded FLAC files calculated MD5 signature gets compared against the FLAC files own stored MD5 signature of the original unencoded data...

FLACTester v1.3 :
http://www.vuplayer.com/files/flactester.zip

-Martin.
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tom_vienna_at
post Sep 8 2005, 08:19
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Thanks for all replies, you are very helpful.

I was also thinking... if anything happens during copying the files from one hd to the other, it would lead to corrupted files. Wouldn't foobar report any corrupted files on playback? Some of you said that this happens very rarely... so I would just re-rip those few corrupted files that foobar reports.

Tom.


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Synthetic Soul
post Sep 8 2005, 09:10
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foobar would (I assume) report corrupt files - but there are just easier ways.

Why use foobar then re-rip, when you can just use an MD5 hash and re-copy? The second option is a lot easier in my opinion.


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