I recently started using Tresorit
as my chosen cloud storage system. I chose it not because of it's price (it is a relatively expensive option) but because my most important selection criterion was security and secondly I wanted a system with a clean, modern, understandable interface. Above all else the system had to offer Zero Knowledge End To End Encryption as well as Two Factor Authentication at the login stage. Tresorit delivers what I wanted.
That said there are always issues to be dealt with when adapting one's workflow to a new system and this short posting covers just one of them, that is how I have decided to deal with the 10GB file size limit, for a single file, imposed by the Tresorit system. It is necessary for me, and I suspect others, to work with this limitation because I frequently have to deal with blocks of data which are larger than this limit, or aggregated chunks of data - in particular large video files. The solution I am using relates only to Mac users because that is the platform I use myself, Windows users will I am sure have their own solutions.
To store a file or a collection of data larger that 10GB on the Tresorit system I first create a disc image of a single folder which contains all the files to be stored and then split that file into segments for uploading, each segment being below the 10GB upload limit. Normally in my case this would be a folder containing files called something like "20120823TripToTheLakes" which will contain all the photos and video files from a trip, the folder may well be tens of GB in size.
To produce a disc image, or .dmg file, it is easiest to use the Disk Utility programme provided as part of the Apple suite of programmes, the programme is found under "Applications", "Utilities", "Disk Utility.app". With that running the easiest thing to do is select "File", "New", then "Disc Image From Folder" from the drop-down menu. Then navigate to the folder containing your files and click "Image". Then give the new file a name and select where you want it to be saved. Because we want to subsequently split this file you should select "Read Only" as the image format. I do not bother in this context encrypting the disc image because the Tresorit system will in any event encrypt the files locally before uploading to the Tresorit servers.
Once those options have been selected click "Save" and the process of generating the .dmg file will commence and when finished you will be able to navigate to the file and mount it as a "drive" should you wish to do so.
This single .dmg file will be a large file which then needs to be split into upload-friendly chunks, I make each "chunk" about 4GB and this is done using a Mac utility called "hdiutil" which is run using the "terminal" application which is found alongside the disk utility application. The Terminal command below, obviously with the names and locations changed accordingly, should be run and this will generate files with the extension .dmgpart with each file being about the size specified as well as a single file with the .dmg extension, all these files will have the same name apart from the file extension.
hdiutil segment -o /Users/Username/Desktop/"Destination Folder"/Destination File Name -segmentSize 4000M /Volumes/DriveName/"Source Folder Name"/"SourceFileName.dmg"
I have used 4000MB in this example which is convenient for many situations and ensures that each file is not too large, if need be one could even write each one of these files to a DVD at some point. If I ever were to want to write DVD versions I tend to change this setting so that data is distributed evenly over the minimum number of disks I can use. Setting a segment size of 4000M(B) will yield a file size slightly larger than 4GB, normally 4.19GB, which is as large a single file as I tend to write to a DVD. A segment size setting of 4500M(B) will yield a single file size of around 4.72GB which is too large a file to reliably write to a single DVD and I like to leave some space as this tends to reduce read.write errors.
Once all the files have been generated by the Terminal command they can all be uploaded to the Tresorit servers without encountering any issues with the 10GB file size limit. If the files ever need to be retrieved from the Tresorit archive it is a simple matter to download them in the usual way and this is where I think it gets really clever. You simply download the "set" of files you require that made up the original file and save these into a folder on your local machine. You then just open (double click) on the first "master" file of the set, the one in the set with the .dmg extension, you can then view all the files as if you were looking at a single file or drive, there is no need to open the other files, they are all just treated as a single file, as if by magic.
If for some reason you did want to re-generate a single .dmg file from the set of .dmgpart files do this: After mounting the disk image using the multipart set, select the disk using the disk utility programme and then select "New Image", provide a name and location etc. and this will create a new single image file from the multipart image.
I hope that's been helpful, it certainly allows me to upload files of folders well in excess of the 10GB file size in a very convenient and above all secure way.