Library/Containers

Question

Hi
I am in the process of consolodating and crosschecking backup data (migrating from one NAS to a different NAS system), the data had been copied down to local external drives ( why = nas was suspect, so I wanted to get the data out in the shortest amount of time, to a temporary 'safe' repository)
In historical copies of docs and library , i.e. periodic copies of the working ~/documents and ~/Libray , the Containers directory is 267GB, with each of the 12 directories within it 22 GB
That each subdirectory is the same size is a bit of a curiosity.
By comparison ~/library/containers on my working MacBookPro ( from which the backups were made pre clean install of Mavericks) is only 593 MB
Other curiosities like com.apple.gamecentre contains documents and libray subdirectories, with the mail subdir at 422MB, and similarly for other subdirectories of ~/library/containers
i.e there is repetrition of library directories under eacm/most of the Contaners sub-directories.
This at first glance would appear to be anomalous, but perhaps it is a residue of some transitional system change...
So can Container directories on backups, be deleted, without affecting the main data e.g. if
containers/com.appl.iphoto is deleted from a backup, is the iphoto library itself, that was also backed up at teh time, affected?
Yes I can test thaht via a copy back etc, but may not spot what is affected...
Links to info would also be appreciated.

Answer 1

The Containers mostly store preferences, but might have other support info unique to the app. It is part of the Sandboxing which gives the app an isolated place to play.
Deleting them might break an app, but I have deleted quite a few without consequence.
However, restoring them is not likely what you want to do, anyway. You'd be copying back gigabytes of stuff that doesn't need to be there.
You should look at the documentation for whatever you are using to back up. It should have a setting to not follow links.