Op 25-3-2016 om 11:02 schreef Carlos E. R.:
Me too.
I have seen software updates rollback in very expensive unix systems (in the million dollar range). With software updates very thorughly tested, because they were fined if the update failed and caused even a minor downtime or some loss of functionality. Even so, they had rollbacks. And that started around 1990 or earlier.
I could not look at the details of how it was done, but I think they made links, storing both the old and the new versions in different directories and made links for the individual files replaced. Depending on how things went out in the field, they deleted the new or the old copy, adjusting the links as were necesary.
Of course, the number of files that had to be touched was limited, compared to a modern Linux.
For more complex updates, they could separate one side of the mirrorred disks, and do the update on one side of the system mirror only. This was done, I believe, for full system upgrades, but might be done for any procedure.
The difference between a rollback and a backup in a sense is that a rollback is instant, a backup takes time. But again, I prefer good backup and restore solutions to be in place for myself. Why? A rollback will only help you in your current system. When you have a good restoration backup procedure, you will become much more powerful. It is just a lot easier for me to achieve the rollback than it is for me to achieve the backup. But again, I feel that they compete with each other, and with more people using rollbacks, less will be interested in having good backup solutions. I feel this to such an extent, that I don't want any energy to go into the rollback, and all of this to go into the backup. Well, that's just me, but I love it in that way. At the same time I was using snaphots to create the backup. But that is just a shortcut really that I don't like. The shortcut involves not having to know your system. I get the advantages for an always-on system. I get the superior ability to do that stuff without interrupting a system. I get that. But I don't like it. Well, that is just the 'opinion' I had wanted to share. That is just my perspective and what my belly tells me really. "Listen to your tummy. The tummy knows." It's just a perspective right. I wanted you to have it ;-). To see it for a change ;-). Right.
So yes, I like the feature. It doesn't mean I'll use btrfs yet... but I'm interested ;-)
For me the reason I have been toying with snapshots is because of LVM. But I never ever did like it. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org