macos - OSX: How can I clone a larger hard drive to a smaller one?

I'm replacing my spinning disk drive with a smaller SSD, because it should make my system much faster[1]. The data I have on the larger drive will fit on the smaller one.

So far, I've done the following:

• Reboot OSX, holding Command + R, to boot into recovery mode


• Use Disk Utility to erase and rename the new drive (plugged into USB with a USB-to-SATA adapter cable)


• Try to restore the main hard drive to the SSD

I get an error like "not enough space on /dev/disk13s2", meaning, I think, "the destination drive is too small." ([asr -source /Volumes/Macintosh\ HD -target /Volumes/the_new_drive -erase -noprompt](http://www.maclife.com/article/columns/terminal_101_make_drive_clone) gives the exact same error.)

Suggestions I've read to fix this are:

• Use some third-party, commercial software instead. I don't like this option because 1) I think it shouldn't be necessary and 2) I want to limit how many pieces of software and companies I trust with my data


• Resize the partition on the source drive to be smaller than the destination drive. This scares me. I don't want to lose data. Is it safe?

To be clear: what I want is an exact clone, byte-for-byte. I don't want any changes to file modification times or permissions, etc. I don't want to reinstall stuff. I just want to boot to the new drive and have it work.

Also, I'm using FileVault on the old drive.

I'd love a solution that uses solely built-in Apple tools (like Disk Utility or asr) or something open source.

How can I clone my data from the larger drive onto the new, smaller drive?

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[1] I've used iopending to see that pending disk operations are, in fact, slowing me down.