Did it make a duplicate copy of all my Events from iMovie 9 , put them in a Folder called Library?
Are they both needed? Can you access either library(Movie Library or Events Library) from either version of iMovie?
I had 450+ gig of events and it seems now it's doubled and almost taking all my hard drive up!!!
iMac (27-inch Mid 2011), OS X Mavericks (10.9)
Yes, when you update iMovie 9 projects and events to iMovie 10 it copies everything from your iMovie 9 events and projects folders into a library package with the .imovielibrary extension. The iMovie 9 folders are left untouched so that you can still use them with iMovie 9. So the disk space required is doubled. If you are sure you don't want to use them in iMovie 9 again then you can delete them, but in that case there is no going back.
Each version of iMovie can only use own format.
When iMovie 10 is first run it asks if you want to update your exisitng material - it doesn't do it unless you let it. I think it updates everthing it can find in projects and Events folders at the root level of all your drives. If you don't want everthing updated you can 'hide' what you don't want updated by temporarily placing the corresponding project and Event folders in an enclosing folder so they are no longer at root level. I decided to update old projects in small steps, each going into a separate iMovie 10 library. I'm keeping both versions until I'm convinced iMovie 10 is worth upgrading to.
In another thread at:
https://discussions.apple.com/thread/5474757?tstart=0
and contary to my comments above, convincing evidence is presented that Apple is using Unix hard links to save disk space. Although both iMovie 9 and iMovie 10 folders appear to contain copies of the each original media file, they actually both link to a single copy on the drive. Your experience of drive space doubling is not in line with this (unless you have your iMovie 9 and iMovie 10 folders on different partitions - hard links can only be used within the same partition).
Interesting!
A further thing I discovered that may be relevant in this thread for anyone wanting to go back to iMovie 9.0.9 after trying iMovie 10..................
In my experience on 2 machines (2007 MacbookPro and 2010 Mac Mini) after running iMovie 10, iMovie 9.0.9 will no longer start in Mavericks but hangs (icon continuously bouncing in dock). In order to be able to run iMovie 9.0.9 again I found I had first to trash the 2 iMovie 10 preference files
~/Library/Preferences/com.apple.iMovieApp.LSSharedFileList.plist and ~/Library/Preferences/com.apple.iMovieApp.plist.
Moreover it is not sufficient to leave these in the trash and the trash will not empty until after restsarting the computer. Only then will iMovie 9.0.9 start. IMovie 10 can be run again but it is then necessary to go through these hoops again to run iMovie 9.0.9.
The trouble seems to be that Apple has used the same preference file name for both versions and iMovie 9 will not run if iMovie 10 preferences are present. On the other hand iMovie 10 will happily "update" existing imovie 9.0.9 preferences.
An update for the record --- It seems that the problem launching 9.0.9 is peculiar to my setup and even trashing the above mentioned preference files doesn't solve the problem any more.
My last paragraph is incorrect since the first preference file mentioned belongs only to iMovie 10 and the second only to iMovie 9
When iMOVIE 10 was installed on my computer..............
