Windows – Hard disk with bad clusters

The longer you use a failing drive the worse and more unreliable it becomes. So if this data is important to recover I would begin backing it up sooner than later. So at this point you might want to skip the chkdsk stuff since you potentially have limited time if the drive decides to stop working altogether.

There are also a number of tools to clone the drive. I find the most reliable to be a tool called dd_rescue. Essentially it makes a bit by bit copy of the hard drive, skipping over any bad or unrecoverable sectors it encounters. This is obviously slow and if the drive is failing to an extreme you might not be able to recover anything.

Another free tool to look at is called Unstoppable Copier. This one is used to recover specific files, which in many cases can be much more convenient than cloning the entire drive (for obvious reasons).

If neither of these tools help at this point, and the data is super important you should maybe consider taking it to a data recovery company.

A couple of most likely causes:

1. You probably have accumulated too many shadow copies that weren't properly disposed of by the backup. This sometimes happens. So try and list them with vssadmin.

2. You are running low on a free space on C:\ and D:. There's no clear guidance on how much space it needs, but having at least 10-20% is generally a good idea.

All in all though, VSS is just ... finicky. It has a lot of dependencies, which in turn are also dependent on other things and so on. If anything in this pyramid break or hiccups, VSS starts spitting out incomprehensible and frequently ambiguous error codes. So even if you google "VSS + ", there'll be a bunch of solutions, each working for just some cases. There is a way to troubleshoot VSS with diagnostic logging, but it is very tedious and it doesn't work reliably. Reimaging the system is simply faster.