We are evaluating DropDMG to purchase for our office.
We are on 10.4.8 and are creating DMGs from upto 7GB Photoshop (PSD) files.
When we create DMGs, they open up fine on the machine that created them.
However, our other office (whom we are ftp’ing the dmg file to) cannot open the DMG files. They get an error “The following disk image failed to mount”. They have tried it on machines running 10.3 and 10.4.1.
We really like this tool, but this is a showstopper for us.
First, I’d check the format that you’re using. For example, the “.dmg bzip2-compressed” format can only be mounted on Mac OS X 10.4 and later.
Second, something may be going wrong with your FTP, either during upload or download. Try creating a smaller DMG for testing purposes. Upload it and then download it back to your same Mac and see if you can open it.
You could also use the “md5” command on the command-line to check whether the uploaded and downloaded files have the same checksum.
I’m not clear on your test. Are you saying that the small file didn’t work via e-mail or FTP? If the small file doesn’t work, perhaps you could e-mail it to me at dropdmg@c-command.com for testing.
Did the name of the unrecognized file still end with .dmg? Did you try getting info on it with DropDMG?
Which FTP program are you using, and is there a way you can set it not to post-process or decode the files that it downloads? Internally BZip2-compressed disk images and standard Unix BZip2 archives look similar. (They both have the same “magic number” at the beginning of the file.) So it’s possible that your FTP program is noticing this and trying to be helpful by expanding what it thinks is a BZip2 archive, but is in fact corrupting the disk image.
One workaround would be to use BZip2 but tell DropDMG to add GZip encoding. This would protect the disk image inside a .gz wrapper.
We emailed a small 44k dmg file and got the same errors as the large dmg file that we had previously ftp’d. Both files are bzip2 format with encoding=none.
I am emailing you a copy of the small test file.
Did the name of the unrecognized file still end with .dmg?
Yes
Which FTP program are you using, and is there a way you can set it not to post-process or decode the files that it downloads?
We are using Cyberduck FTP at each office on the upload and download.
Internally BZip2-compressed disk images and standard Unix BZip2 archives look similar. (They both have the same “magic number” at the beginning of the file.) So it’s possible that your FTP program is noticing this and trying to be helpful by expanding what it thinks is a BZip2 archive, but is in fact corrupting the disk image.
One workaround would be to use BZip2 but tell DropDMG to add GZip encoding. This would protect the disk image inside a .gz wrapper.
I have tried your test file on an Intel Mac running 10.4.8 and on a PowerPC Mac running 10.4, 10.4.1, and 10.4.8, and it worked successfully on all of them. (I don’t have a G5, however.) Will continue discussing this with you via e-mail to try to figure out what’s going wrong, but at this point I don’t think it’s a problem with the .dmg file.