Yeah, the new BE does not over write anything. It takes a ZFS snapshot of the file system before it updates or changes anything and if you don't like the update, you can roll back to the ZFS snapshot and your system will be in exactly the same state it was in before you did the update (hence the terms "snapshot" and "rollback"). Check out these links for an explanation on how to do it:
http://www.blastwave.org/dclarke/blog/?q=node/113 http://www.blastwave.org/dclarke/blog/?q=node/110 In particular, look at the second link and scroll down to the part where it says: OpenSolaris has the ability to create multiple boot environments or BE's. You can take a snapshot with ZFS of the current boot environment for later rollback or you can upgrade forwards and have both a future release as well as the current release as separate boot environments. You need to use beadm(1M) to manage the boot environments.... What you are looking at far surpasses the idea of a journaling file system. This is a revolutionary technical leap in systems management. Think about the implications of a system where you can apply patches and updates as well as complete kernel changes but with total safety. You always have the ability to roll back with the flick of a switch. For that matter you can not do damage. The OpenSolaris system can be unbreakable in that you can always roll back from any update or system change. If you blink twice you may miss that fact that this is a non-trivial paradigm shift in computer systems management. For anyone that has ever been trapped in a server room at three in the morning, cold coffee in hand and sweat forming in the palms. For those of us that know that there is not enough time left to recover from a significant server change after your systems recovery window passes. For those of us that have never exposed users to downtime at 7 AM in the morning I suggest that you consider the benefits of being able to say ?gee, that doesn't look to be working .. let's roll back to the previous good state?. And then be able to do it. In the snap of a finger. It can change the whole game. Does anyone else see the significance of this boot environment facility other than me? I certainly hope so. I said it then and I say it again : Every serious scientist or engineer will want to stand on the shoulder of this giant. OpenSolaris is the cure for the common computer. -- This message posted from opensolaris.org
