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hopper64's avatar

Trouble transferring data between external drives - shrinking file size?

Asked by hopper64 (2 points ) November 12th, 2008

I am trying to transferring all my data from a journaled firewire 500gb drive (which is almost full and needs to be reformatted) to a 1tb USB2 external drive partitioned into 3 sections 2 of which are unjournaled and I seem to be loosing file sizes in the process.

I have tried transferring the data (a range of video, photos to documents) in a couple of different ways (large folders to single files) and it the sizes seem to be slightly (inconsistently) smaller. e.g. photos from 37mb to 36mb or 1 folder from 20.16gb to 20.08.

Is it something to do with journaled vs unjournaled drives? Is it unimportant?

I just want to know if I need to start again with the transferring of my data or if their is a explanation for the random file size decreases and it is okay?

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6 Answers

squirbel's avatar

Hopefully you get someone to answer here.

I was curious about this, so I started googling. These are my results.

http://support.apple.com/kb/HT2355

Journaling doesn’t seem to have any meta-data. This is probably what you were thinking was being stripped from each file in the transfers. It’s possible that it is meta data of some sort, but I don’t believe the journaling is the cause.

Here is someone who agrees with me, read their response at the very bottom of the page.

“Too late to include in my last reply, I noticed your comment about needing to copy the files to an unjournaled partition somewhere. Journalling doesn’t have any effect on file size or fragmentation—it is essentially a method of recording pending file changes so that should that process be interrupted, the file system knows what files might be out-of-date without going through the entire file system.”

TheBox193's avatar

The original drive my be fragmented. When the files are written to the new drive, they will be written with no to less fragmentation.

I recommend de-fragmenting the original drive, then see if the content sizes are closer.

also, if they are different file systems (FAT32, NTFS, ...) there might be a slight difference maybe… I don’t know.

hopper64's avatar

Cheers ,how do I check if they are different file systems?

Also I have attempted defragging on a mac before with little success, but will try it.
Was curious if that might be the reason especially because the drive is so full.

TheBox193's avatar

if your on pc you can open ‘my computer’ right click on each of the drives and go to ‘poperties’. On the window it will say “File system: NTFS”, “File system: FAT32”, or something else. I don’t really know if that will make to much of a difference. Does anyone else here know perchance?

squirbel's avatar

Macs don’t use NTFS or FAT32.

hopper64's avatar

Thought that might be the case.
But could it really just be the fragmented files?

I just can not see any other easy explanation.

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