weird problem: when saving images to our NAS (a WD My Cloud EX4100) using paint.net, the reported "size on disk" is hundreds of kilobytes larger than the actual file size. this amount does not directly correlate to the size of the file; i checked a 28 MB file, and the size difference was ~200 KB, compared to the nearly 800 KB in the above screenshot. re-saving the image in another program, e.g. IrfanView, strips this excess data, as does copying and pasting the file in Explorer. it's clearly not part of the actual file, so it must be some kind of metadata stored alongside the file in the filesystem. a cursory internet search suggests some kind of image indexing/thumbnailing may be happening, but the associated services don't seem to be present in the control panel, and again, it only seems to happen when saving images in paint.net. anybody know what the fuck is going on here?
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in reply to @rachelmae's post:
Try Get-Item -Stream * .\path-to-image-file in a Powershell prompt to see if your file has alternate NTFS streams.
If you have shell access to your NAS, assuming it's using ext4, try getfattr -dm- ./path/to/file for the moral equivalent, and see if any extended attributes show up.
but the associated services don't seem to be present in the control panel
I'm leaning toward "Paint.NET is saving an alternate stream with your file". You don't need a service to do this... browsers will do this already for files you downloaded, and Outlook adds its own stream as well.
i tried the PowerShell command on two files (one with the extraneous data, one without) and didn't see anything out of the ordinary. this is on a network share mapped as a drive letter, would that affect anything?
as for shell access, i have no idea...
this is on a network share mapped as a drive letter, would that affect anything?
SMB supports Alternate Data Streams (took me several minutes to find a reference: https://support.vastdata.com/s/article/UUID-9907cdf3-5ba4-b347-c082-af2011b6f240). So not sure what's going on. Paint.NET only does this when saving to the NAS?
With that being said, I am able to contrive a similar scenario to yours: http://gopher.wdj-consulting.com:70/store/dnYjW4FyPX.png
(Please ignore the 109 vs 113 byte size difference. I added text and forgot to rerun dir /r.)
yeah, only PDN, and ONLY when saving to the NAS. local files are the expected size. bizarre!!
i can simply copy and paste a folder in Explorer and it will apply the correct size to all files within. i'm at a loss...
I'm sticking by my current guess (PDN is saving data to an alternate data stream). But it is bizarre to me that it's saving an alternate stream over a NAS, and only over a NAS. Without having access to the NAS itself, and knowing which filesystem the NAS is using, I can't really help further :(.
I was going to suggest "Maybe send me the offending file and I'll save it to my own NAS, where I do have shell access". But seeing that my NAS system is running Linux and using zfs, I don't know if I'll be able to duplicate alternate streams losslessly ("Please note that most file systems have severe limitations on the size of xattrs."- this is in fact one key difference between extended attributes and alternate streams).