Comment by nyrikki
15 days ago
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.
> Block level copies of boot volumes is high risk, because they are almost exclusively mounted in RW mode via label or guid
Oh, 100% agreed. The article was about "under duress", and that's about the only time where I think this is a useful imaging approach :) (I.e. I'd mostly use this in the "I don't know if this'll ever start up again" case)
You shouldn't land in this situation in the first place. Ideally. But, as the saying goes, "in theory, theory and practice are the same - in practice, they are not" ;)
Stuff goes wrong. This is a good tool in the toolkit for when it's already gone seriously wrong.