Comment by nyrikki

Block level copies of boot volumes is high risk, because they are almost exclusively mounted in RW mode via label or guid.

Pretty common problem for someone to do their boot drive, reboot and have it mount their backup.

If you are using iSCSI or anything with multipathing this can happen even without a reboot.

I know that block level copies seem like a good easy solution. But several decades in the storage admin to architect roles during the height of the SAN era showed that it is more problematic than you expected.

To be honest, full block level backup of a boot volume is something you do when the data isn't that critical anyways.

But if you use case requires this and the data is critical, I highly encourage you to dig into how even device files are emitted.

If you are like most people who don't have the pager scars that forced you to dig into udev etc... you probably won't realize what appears to be a concrete implementation detail is really just a facade pattern.