Yosemite "Warnings": how to avoid problems
Euan Williams 1. The Drive Health Spa
Do all housework and health checks on your existing installation (of, say, Mountain Lion or Mavericks). This should include Disk Utility repairs to Disk Permissions as well as verifying the disc data structure (Verify Disk).
If Disc Utility reports (in red) that a repair is required but not possible on a running disc, then restart with the Option key held down (or cmnd + R) before the chime. You should see a row of available startup options including Recovery Disk. Choose Recovery Disc if available — it’s on a hidden partition. Otherwise an external drive or another partition will do if it has a recent OS X version installed. Now run Disk Utility from there for the Repair Drive function.
NB. Permissions should be repaired from within the active disc or partition you are running, and preferably not from Recovery Disk or other setup.
For the best possible system health do a “safe boot” as well, before cloning: start up with the Shift key pressed until a progress bar appears. This will be slow, as will the next, normal, startup. The words ‘Safe Boot’ will appear somewhere in the login screen. Log in, then don’t forget to restart normally. Among many other things, Safe Boot wipes software caches which are sometimes the corrupted ‘little offenders’, and these will be re-established fresh at the next normal startup.
(When in Safe Boot, Finder windows will ‘shake’ as you scroll them (Mavericks), or show random foreground-background horizontal display stripes at late startup (Yosemite) which stop when startup is complete. This is a deliberate reminder that you are in Safe Boot. Don’t forget to restart normally afterwards.)
2. Your Backup Clone
Why not use Time Machine? Use cloning to avoid migrating lots of historic data that you may not want in your new installation. Tm/C is useful, but not a “solution to everything” for a very wide range of reasons. Look it up on Wikipedia, or visit > http://pondini.org/TM/Troubleshooting.html <. Don’t ever be lazy about backups.
Make a clone of your drive or partition on a freshly erased partition or drive, preferably an external one. Carbon Copy Cloner (www. Bombich.com) or SuperDuper (www.shirt-pocket.com) will do this, I use CC Cloner.
If in doubt, clone “everything”. Check that the clone software acknowledges that you are about to create a “Bootable” clone. If there are big files or folders that YOU have created (and you don’t want to clone) you can exclude them, BUT files with “.” in front (invisible files), and files with weird names such as “Var”, “Usr” “Tmp” etc, etc, are essential parts of your OS and SHOULD be cloned.
Until you are quite clear about settings it is better not to use cloners for auto-backups. You don’t want to overwrite or erase important data by mistake. Stick to basic cloning to freshly-erased partitions, drives, etc.
3. The Fresh Install process
Laptops: make sure you are connected to a reliable power supply. With Disk Utility, erase a partition or your internal drive so that it is ‘clean’ “MacOS (extended) Journaled”.
Download, and make a backup of, the “Install MacOSX 10.10” file from your Applications folder (the original may disappear after installation is complete) then install a fresh copy of OS X Yosemite from the downloaded installer.
Let the Installer restart your Mac to complete the process. It will choose the correct drive/partition, and may chime a second time during the restart process. Don’t shut down, or close the laptop lid until this restart is complete and everything has settled down.
4. Migrating Data
Use Migration Assistant to transfer your older settings and files from your fresh Clone. If Yosemite install or migration seems to stall, don’t panic — just walk away and be very patient (that’s “very, very", and sometimes even more "very” patient).
Enjoy Yosemite, it’s good, and virtually all my Mavericks software runs just fine, the rest needed the odd update.