10go PSB compressed to ZIP: is it fine/safe?

Are you aware that you can turn compression for PSD and PSB files on and off in Preferences File Handling? Compression gives smaller files on disk but those smaller files take longer to save and reopen as they have to be compressed/decompressed during the save/open process. The advantage though is that the compression is lossless and was designed to work inside the PSB file format. Personally, I prefer the save and open speed advantage of saving without compression, and Ilive with the larger files on disk, but I recognise that is a personal choice.

For back up, I use Macrium Reflect which works automatically to a schedule and allows the restoration of any files or even the entire system. I think it is Windows only, but if you search for Mac back up & cloning software there will be similar.

Dave

Zipping multiple PSB files adds an additional point of potential file loss.

See it this way: suppose you saved your files to an external backup drive. You saved a bunch of PSB files in one folder to that drive and a zipped version of that folder with PSBs.

Now suppose that the backup drive's file system is corrupted for some reason (for example, due to a power outage or a system crash while saving another file to that drive).

Your attempt to fix the file system is only partially successful: the folder with the PSB files and the zipped folder with PSBs are affected.  So what are the chances of rescuing our data compared for each?

First you check the folder with PSB files. It seems that out of all the PSB files (let's say 5) 2 files are corrupted. Because each file was saved separately, 3 files are fine. Then you use various PSD/PSB repair tools as well as opening the PSB in Photoshop or other image editors. One of the PSBs you can repair, and the other file at least could be partially opened in another editor, and you saved a few layers.

Now, your chance to repair and rescue all or part(s) of the PSB files in the ZIP archive is (much) smaller, because:

(a) all PSB files are part of that ZIP file.

(b) there is almost no redundancy built into a zip file (unlike proper backup tools that compress the files). That means you need to somehow rescue all data for each PSB that is zipped.

(b) it depends wholly on which part of the datastream in the ZIP file is damaged. For example, if the compressed data stream is corrupted somewhere at the beginning of the ZIP file, chances are you will not be able to recover any of those files without dedicated zip recovery tools. Or if the data errors/CRC errors persist for different files throughout the corrupted ZIP file: that going to be a tough nut to fix, if it is possible at all. Or if the headers are corrupted, we would need to manually fix those headers. If the ZIP's "dictionary" is kaputt, and there is no second copy saved or that second copy is also toast: no way to save any of the files (what I understand).

Anyway, from personal experience: at some point I thought it was a good idea to save work files in a ZIP file as an archive on a USB drive. That archive got corrupted. I failed in repairing and retrieving any of the files, despite my best efforts. All was lost.

Had I saved those files individually in a folder on that drive, I would probably have been able to repair and rescue the majority of my files. Had I used a proper backup utility to create a compressed backup of all my files: I would probably have been able to repair and rescue most of my files, if not all, as well even with a corrupted and repaired file system.

If you want to compress your files for archival purposes, my advice is simply:

- NEVER use a regular compressing method (zip, 7zip, etc) to do so. You merely add additional potential points for corruption and file loss.

- DO archive your files using a proper backup utility. Those tools add various levels of redundancy, and will be able to retrieve and repair most if not all your compressed files even if they are subjected to certain levels of corruption.

In short: ZIP is not a valid compressed archival format. It is too fragile for that.

If you can live with a very time consuming save process, I suppose it's fine.

Does it really matter if it's 5 or 10 GB? These are big files either way, they will eat up your disk space sooner or later, and it feels more important to have a long term strategy for expanding storage capacity as you need it. You're just slightly postponing the inevitable.

How will you back up? Pre-or post-zip?

Hi!

Do you need to send your layered file to work? If not, just flattening the image and saving it as a .psd file will save you lots of room, which then you can upload it to a site like WeTransfer, or Dropbox and not be worried about compression. Or if you have a large enough Dropbox account, you would not even have to flatten it. I am, like you, concerned about any time I add compression to a file. You may not see any issues now, but I am not sure if a file is affected every time you compress it like a jpg file comession. I would be interested in the comments by others here in the forums to see their opinion, but I am not a fan of compressing anything unless it is the final output, and I aways keep my original files. 

Michelle