horizontal colored lines appearing after saving a PSD in PS

[paolofus]

i recently bought a mac mini2, installed PS and LRC (all updated to the last version), and started working on my photos.

Now, randomly, when i finish editing a photo on PS, evertything looks fine.. until I save the photo.
The very nexy moment, the photo has a horizontal colored line, that appears in PS, LR, Finder preview...

the photo is a PSD produced by PS after i've worked on different raw files layered and then merged on a single layer. a workflow I've done for years, with no problems until now

In one occasion, the line has disappeared for no apparent reason.

I'm going crazy...

[Kevin Stohlmeyer]

@paolofus where are you saving to? This looks like a corrupted file from saving to an external or server.

[paolofus]

it's an external ssd drive. i run a "s.o.s." utility disk diagnostics on it, with no negative results

[D Fosse]

At what precise moment does this appear? When you are flattening? When you are saving? When you are reopening the saved file?

Are you saving directly to the external drive? That's not recommended. Save locally, then copy over.

I agree that it looks like file corruption, but determining where the corruption happens can be difficult.

[paolofus]

it happens when i'm closing the file and saving. as soon the file is saved, it appears with a line wherever you open or preview it

[Kevin Stohlmeyer]

@paolofus what happens if you save to your local drive? Saving directly to an external is not a supported workflow for Photoshop.

[paolofus]

@Kevin Stohlmeyer i'll try doing so from the next project on. but i've been saving directy to external drives for years with no issues

[D Fosse]

That's the kind of thing that works until it doesn't 😉

[Diamantis23750061658e]

Same thing happens to me but only the last month or so although I've been directly working and saving to an external ssd for years now.

[Kevin Stohlmeyer]

@Diamantis23750061658e does the same thing happen when saving local? Drives can go bad

[Diamantis23750061658e]

I constantly work on an external SSD so I wouldn't know. The SSD seems to work fine though. One more detail: while working on a photo, I save. But this issue occurs only when I save AND CLOSE the file.

[D Fosse]

Well, it shouldn't be too difficult to test? Save local for a while.

Working directly to an external drive is not recommended and never has been. It's just a bad habit. Adobe officially warn against it. Yes, it may work perfectly for a while. And then one day it doesn't.

[Diamantis23750061658e]

That's actually what I'm doing right now. The thing is that it happened just 3 times the last couple of months. So I'm gonna have to save locally from now on to reach to a conclusion in the next month or so .

[D Fosse]

What we can say for certain right now, is that file corruption is always caused by failing hardware.

External drives is high up on that list. It doesn't have to be the drive itself - frequently overlooked is worn cables and connectors. It only takes a nanosecond broken connection. Don't move or even touch the drive while it's writing.

[Diamantis23750061658e]

As you may have read I'm facing the same issue. But I have one question: while working on your file I guess you save every now and then. Has it ever occurred while you are saving or the line only appears once you save AND CLOSE the file? Because this exactly is what happens to me. The colored line appears only after I close the file. I mean, for the rest, my external ssd works fine and this makes me wonder whether it is actually a hardware issue or not.

[paolofus]

I've started to work only on the mac HD, not on the external SSD, and that seems to have solved the issue.
the colored lines only appear when i close the fine, after saving, and open it on LR. But again, as many has pointed, it could be a working-on-external-drive issue

[paolofus]

NEW UPDATE: I bought just yesterday a new external SSD, because the storage space on the Mac HD is too small, hoping the problem was with the old SSD.

Today, I already got the first image with an horizontal colored banner...

[Kevin Stohlmeyer]

@paolofus did you reformat the external drive to Mac Compatible?

[Kevin Stohlmeyer]

What you should be doing is storing everything on the external, then dragging over to local to edit, then drag back to the external when completed. Not working directly off the external.

[paolofus]

yes, formatted the new SSD yesterday as soon as I connected it to the Mac.
I just can't imagine how could I work on the photos dragging them back and forth from the external to the interior HD everytime I need: it would slower all the process, mess with the LR catalog and be a huge risk of chaos in handling the files.

I shoot tens of Gb every week, and keep projects "under-construction" for weeks. I need to have the files on a big enough HD and be able to work on that same HD. 
I've been working on external hard disks for years, I know tens of photographers who do so, and nobody ever encountered this problem...

[D Fosse]

Until now.

It's not that it doesn't work. It's that the risk of file corruption is very much higher. And that's what just happened to you.

The problem isn't the disk itself. It's cables and connectors. The drive is constantly connected and disconnected, it is moved and bumped around, and it's inevitable that the connectors become looser over time. A save is much more complex operation than a simple transfer, taking more time. All this increases corruption risk.

It only takes a nanosecond broken connection for a file to become corrupted.

If you absolutely have to work off external drives, prioritize. Move things off your system drive and over to the external, rather than leaving it, forcing you to work directly on the external. Take your precautions. Make sure the connectors fit firmly. Replace all cables at regular intervals. Do not touch the drive when transfer is in progress! Walk away until it's finished.

[paolofus]

i see your point, but the Mac is new, the HD and cable are one-day new, I don't disconect them ever and I don't touch them while working on them...

[D Fosse]

This is very easy to find out.

Work on the local drive for a while, a month or so. If you get any corruption during that time, come back and I'll reconsider.

Something in your hardware is corrupting your files. So you have a choice. You can either take some precautions, or you can take your chances.

[paolofus]

I did so. I worked on the local HD, and no corruption happened, so I thought it was a problem with the external hard drive I was using...

BUT, yesterday I bought a new external drive (with its own new cable), formatted it, connected it to a never used before port and started using it, and today I got the first corrupted file already. The chances of this being a hardware problem seem quite low at this point..

[D Fosse]

I think that proves my point very conclusively. Save to local drive, then copy over. Don't save directly to an external drive.