I want to do a Time Machine backup and it's not the first time I do it in this external hard drive, so Time Machine is doing the "preparing backup" step since a few minutes. As it's been quite long I haven't back up, I know this step will take a while.
However I have no idea how far is this step, is it 5% ? or is it nearly done and 95% ?
How to know how long remaining ?
Best Answer
If the CPU goes over the roof, as shown by Apple Activity Monitor (mds–stores) or MenuMeters (see below), Time Machine "Preparing backup…" takes forever when it should be done in seconds or similar, and Apple Mail and Finder Spotlight (File - Find) find nothing, chances are that Time Machine is checking the Spotlight FSEvents database to see what has changed since the last backup, and that that such database is corrupted or there is some other problem. The fix is:
In my case, that worked like a charm on macOS 10.12.6 (16G2136) Sierra using internal booting SSD 2TB from Apple (Samsung) on iMac 27-inch 5K Retine (mid 2017) and external Time machine Samsung Portable SSD T5 2 TB. Time Machine takes about 15 seconds to perform each backup there!
Finally, it is a good idea to install MenuMeters to easily see when the CPU goes over the roof… MenuMeters for OS X El Capitan 10.11 (and later) https://member.ipmu.jp/yuji.tachikawa/MenuMetersElCapitan