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Corruption in large Photoshop files

By grant@rb ·
When transferring large files, a chunk of the image gets misplaced. It looks like the a piece has been cut from the corner and pasted in the middle. Contacted Adobe and they blame the network.

Corruption occurs:
-randomly when going through a router
-never when going through a switch
-may be related to transferring files from PCs to Macs

If I switch to the desktop, problem disappears. I can't do this in all cases. I need a different fix.

1- How can I prevent the file corruption from happening?

2- Alternatively, how will I know when the corruption occurs, so I can redownload?

Bonus pts for good answers for 1 or 2.

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Corruption in large Photoshop files

by TimTheToolMan In reply to Corruption in large Photo ...

Hi,

I'm not a Mac user so forgive my ignorance... You say "If I switch to the desktop, problem disappears". What does that mean? I think its going to be crucial to the fix.

I can tell you this, though... The TCP protocol allows for packets to be transmitted out of order. Its built in to the protocol. Each packet has a transmission id and they're reconstructed at the far end in the correct order.

Unless your router is actually corrupting the packets' id, then the network cant really be to blame. If the router *was* corrupting packets, then you'd see problems with other files that were transmitted too.

Hopefully I may have a shot at answering 1 when you've helped me out a little...

As far as two goes... You could add a watermark to the image and verify it was intact after the transfer.

Cheers,
Tim.

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Corruption in large Photoshop files

by grant@rb In reply to Corruption in large Photo ...

The file corruption is semi-random. It never occurs when the transfer goes through a switch. It only occurs when the file goes through a router.

It is obvious when the file is corrupted; a watermark by itself is a redundant check that would nothelp. If we had some software that could check the correct-ness of the watermark, that would be useful. (ie Software X tells me that the watermark on files 10, 11, and 12 is not correct. I would look at those three files and see if they got corrupted. If so, I could contact the artist and say resend.)

We transfer a number of files, so it is not feasible to manually check every one.

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Corruption in large Photoshop files

by grant@rb In reply to Corruption in large Photo ...

Point value changed by question poster.

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Corruption in large Photoshop files

by TimTheToolMan In reply to Corruption in large Photo ...

Hi,

OK, if you dont want to open the files manually to check them...and I can understand that... then one option you'd have would be to zip them at the far end and unzip them when they've been copied. This could be automated...

If the zip filegets corrupted, then it wont unzip and you'll know you have to re-copy.

Besides, a zipped file will copy a little faster and some of the time you lose in the zipping and unzipping process you'll gain in reduced copying time.

The trick will be to automate and synchronise the two ends of the process to be completely automatic.

I also thought about doing a CRC check on the files at each end, and compare the values, but I think the zip method is actually better.

Obviously the very best thing to do is to find the cause of the problem, though! This is more of a workaround.

Cheers,
Tim.

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Corruption in large Photoshop files

by grant@rb In reply to Corruption in large Photo ...

Thanks for the zip workaround, but it won't work in my situation. I'm looking for something real-time. When I open the file, I can tell if it is corrupted. I need something that tells me that the file transfer was bad when it occurs. I may not look at the file for a week. By then, it may be too late to go back and have the file resubmitted.

I heard someone else with a very similar problem. I reasoned that, if two people in my sphere of influence are having this problem, more people have had this problem and they've probably fixed it. Again, I need a real-time fix/check.

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Corruption in large Photoshop files

by TimTheToolMan In reply to Corruption in large Photo ...

Hi,

It would be a real-time check. As I said, the trick is to automatically zip at the far end, before the copy and as part of the same process, unzip it when it arrived.

This would be an automatic process involving a small program - but perhaps as simple as .bat file.

One thought would be - if the files were to be copied from a known location, you could have a scheduled task to run say every 5 mins that looked for new images and zip them...

...then at the copy-to end, rather than simply drag and drop them into a folder, drop them onto an icon on the desktop which unzips them for you.

The code to do this is simple on a PC and I'd be willing to write it for you. But I'm not really sure about the Mac end.

At the end of the day you need to do something to the file at BOTH ends of the process - whether thats to use a CRC check to produce a signature of the file and then re-produce the signature after copying - and check they're the same... ....or the zip idea. You still need two processes.

Of course, fixing the problem is the best solution. You haven't yet mentioned what you mean by "If I switch to the desktop, problem disappears"

If you let me know what that means I may have a better idea of why its happenning....

Cheers,
Tim.

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Corruption in large Photoshop files

by grant@rb In reply to Corruption in large Photo ...

Thank you for the ideas, especially the *.bat file. You are correct that we would need to check both ends of the process. It sounds like it would work, but it is quite labor intensive. I need something that is idiot proof.

When I posted thisquestion, I was hoping someone would say, "I'm had his problem and I solved it by 123."

Switch to the desktop is a networking term. Some network are designed so that the users are connected to a hub and the hub is connected to a switch. Other networks are designed so the users are connected directly to a switch, aka switched to the desktop. Still other networks are a hodge-podge of the 2 methods. My questionable network is a hodge-podge. My users who are switched to the desktop never have a problem. My other users randomly have it.

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Corruption in large Photoshop files

by jfitz In reply to Corruption in large Photo ...

Hi-

We had this problem opening PS 6.0 files across the (Macs to
NT server running SFM)network then doing the manipulation
on the Mac and re-saving back to the network drive.

To remedy this problem we now copy the file from the
server to the Mac work on that file save it to the mac and
copy the file to the network drive, so far it works fine.

Also mack sure you have enough space on your "scratch
disk" and you have optimized the data so that it does not
fragment.

Good Luck.

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Corruption in large Photoshop files

by grant@rb In reply to Corruption in large Photo ...

Poster rated this answer

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Corruption in large Photoshop files

by grant@rb In reply to Corruption in large Photo ...

All right, jfitz@pdidesign.com, that's the kind of answer I'm looking for. I thought that someone else out there would have found the same problem. I'll try to save on the desktop. If this works, I'll award you the points.

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