A file type restriction in a cloud backup plan is a restriction on the sorts of files that can be backed up.
There are a few ways that the online backup service can restrict certain kinds of files but it's usually done by simply excluding files with certain file extensions from within their software.
For example, let's say the online backup service you're using restricts the backing up of VMDK files, a commonly restricted type of file among backup plans that have this kind of restriction.
If you've chosen the your "Virtual Machines" folder to be backed up, and it contains 35 files, 3 of which are VMDK files, only the other 32 files will be backed up - yes, even if you have the entire folder selected for backup.
Is a Backup Service That Has a File Type Restriction Worth Signing Up For?
We wouldn't exclude a particular cloud backup service from your consideration just because it restricts certain types of files.
In other words, we don't think you need to take an ethical stance just because they do it. It really might not be a big deal, depending on your situation.
What we'd do next is find out which types of files they restrict. Information you'll be able to find on their website.
What Types of Files Are Usually Restricted?
Of the backup services that restrict certain types of files, most only restrict files that are typically extraordinarily large or problematic to restore properly.
For example, Backblaze, one of our favorite services, initially restricts the following types of files: wab~, vmc, vhd, vo1, vo2, vsv, vud, iso, dmg, sparseimage, sys, cab, exe, msi, dll, dl_, wim, ost, o, qtch, log, ithmb, vmdk, vmem, vmsd, vmsn, vmx, vmxf, menudata, appicon, appinfo, pva, pvs, pvi, pvm, fdd, hds, drk, mem, nvram, and hdd. They also restrict all files within certain system folders.
Many of these file types you've probably never heard of. Some of them, like EXE files, which are major parts of the programs you run on your computer, don't usually restore properly so excluding them from the backup makes sense.
Others in the list are typically very large, like the already-mentioned VMDK virtual machine files, as well as image files like ISO. Others, like CAB files and MSI files, are program and operating system setup files, which are already on your original program setup discs or downloads.
Backblaze is really smart about file restriction, as are some other of our favorite services. Not only that, Backblaze lets you remove any of these restrictions at any time. So in their case, in particular, it's only an initial restriction. If you really, really want to back up your 46 GB VMDK file, just remove the restriction and have at it.
No service we've ever seen restricts common files like JPG, MP3, DOCX, etc. Some cloud backup services do limit video files or only allow video files to be backed up in higher-priced plans so be sure to check for that in my review of the service or on their website.
Why Do Some Backup Services Restrict File Types?
Like we already mentioned above, the goal of file restrictions is to limit files that are difficult or needless to restore or that are really, really big.
In case you haven't guessed, at least in the case of really large files, not having those backed up to the cloud backup provider's servers saves them a ton of money in storage costs. So oftentimes, a file type restriction is really just a way of lowering the cost to the company.
Cloud backup services that only initially restrict file types do so to help speed up that large, initial backup that everyone has to go through. This is actually a really good idea because it gets your more important stuff, like your documents, music, and videos, backed up first. See our Online Backup FAQ for more information on the first backup you'll perform.
Once that initial backup is over, you can go remove the restrictions to get your less important data safely into the cloud.
Some backup services have a different, or sometimes additional, way of restricting really large files. This is referred to as a file size limit and is somewhat less common than file type restrictions.