Comment 21 for bug 320638

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xor (xor) wrote :

What you people are forgetting is that RAID1 is in fact the PERFECT backup solution:
It takes a low level copy of the whole system while the system is *running*, and as opposed to cp/rsync, the copy is *coherent*:
Programmers do NOT design software to be robust against their files being randomly copied one after another by an external cp/rsync. How is this even supposed to work? If you copy file A, then file B, nothing guarantees that the software does not modify one of them in between your copying in a way which makes the files incoherent / breaks their compatibility.
And with regards to backup, we're talking about copying whole operating systems, consisting of *thousands* of programs. I would say the probability among thousands of programs is 100% that at least one of them will have its data corrupted if you copy its files using cp/rsync while it is running.

As opposed to that, a RAID1 is always in complete coherence if you shut down the system before you remove the disk. There is no mismatching data in multiple files. You can immediately boot up again, so backup takes 1 minute.
You could of course take offline the system for cp/rsync as well to get coherent data, but that will give you *hours* of downtime because the copying needs to happen while the system is offline. RAID1 can copy while it is running!

Overall, this bug is the worst issue in software design I've encountered in years, and I'm almost screaming :( I have spent over 20 hours migrating my machines to RAID1 so I can reduce the backup procedure from >5 hours to 5 minutes, and now it just doesn't WORK.
This is infuriating :( Can someone *please* come up with a fix / workaround?
I would be willing to pay a bounty of 50 EUR in Bitcoin for this to be fixed.