What is the most reliable way to send files to another Mac over wifi?

1. Compress entire folder of files on source Mac.
2. Calculate checksum on resulting zip file.
3. Copy zip file to target Mac.
4. Calculate checksum on received zip file, from target Mac.
5. Decompress zip file.

There are other approaches. This is a fairly easy one.

truth1ness said:

Nice, thanks. Would simply putting the files into a DMG, ISO or some kind of package file accomplish the same thing without having to wait for it all to get compressed?

Click to expand...

Those would work, but you should test whether they're faster than zipping. It may be that disk I/O is the slowest part, copying data to an uncompressed DMG will write the same amount of data as the original files. This could take longer than compression, which writes less data by nature.

I also second what dyt1983 wrote about transferring large files over an unreliable connection.

If you can't directly address the connection's reliability, consider a sync program. Look for one in the Mac App store. I have no recommendation, but there should be plenty of candidates.

Finally, consider whether the problem may lie with your "network drive". You gave no info about it, but if it's causing the problem, there's not much the source Mac can do to remedy that. At best, it can detect failures and resend, but ultimately the target needs a minimum level of reliability.

truth1ness said:

I think all DMG's include a checksum. If you do a google search for "dmg checksum" you'll see a lot of help threads asking about an "Invalid Checksum" error when trying to open a downloaded DMG, so in theory a DMG should have the same integrity as a Zip and not need an external checksum, right?

Click to expand...

I wasn't sure that every DMG has a checksum, and suspected they didn't, so I had to look it up.

The shell command 'hdiutil' is the command-line interface to the disk-image functionality. Its man page is here:
https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man1/hdiutil.1.html

On that man page is this:
(Red hilite added.)

Based on this, I don't think a read/write DMG has a checksum. You could test this by running the 'hdiutil' command on the target Mac. If you need an exact command-line, just ask.

The reason you see "Checksum errors" on downloaded DMGs is that they're read-only or compressed.

You could produce a checksum by creating the DMG as read-only or compressed, but I suspect that's going to take about the same amount of time as making a zip file. You won't need to unzip on the target Mac, just mount the DMG (which verifies its checksum), and copy the files off the DMG.

The 'hdiutil' command also has a 'checksum' command, which can be performed on any DMG type. You could setup an Automator workflow to do this, show it to you, and then you run the same workflow on the target Mac and manually confirm.

If I were doing this rigmarole more than once a week, I'd definitely look into a sync app that handles it all for me. Even if it's only once a week, I'd probably get sick of it in a couple months and again look for a reliable sync app.