iCloud Drive loses files
I copied all my folders to iCloud drive from my macbook pro running Yosemite. The folders contained all my documents (word, pdf, excel, powerpoint etc) in various subfolders. Since there were a large number of files, I copied them in stages, one folder at a time, although each of these folders contained a number of subfolders. In total, all the files amounted to about 20GB (I purchased 200GB of space) The uploads took a long time, but I waited till the progress bar against files in the top level folder showed that it upload was complete. I then went into Finder and deleted the original copies in my Documents folder on my local hard drive. I have now discovered that random files are missing from iCloud drive. Subfolders are either empty or contain only a fraction of the total number of files they are supposed to contain. The files that are missing are not only large files, many were under 100KB in size. Clicking on Get Info shows that only 8.12GB of data exist on iCloud Drive.
I work away from home a lot and had planned to access my files through iCloud drive. It is impossible to rely on it, if random files are lost (or fail to upload) with no notification at all. It is impossible to know which files are missing until I need them and then discover they no longer exist. My files were safer when i simply travelled with multiple hard drive back ups.
My question is - have I done something wrong or is this an inherent fault with iCloud drive? If it is the latter then I will simply have to avoid using it (and would value advice on reliable alternative options), because I cannot take such a risk with my data.
Thanks for your help
MacBook Pro (Retina, 13-inch, Late 2012), OS X Yosemite (10.10.2)