HELP, All of a sudden my drive pools are offline?! I can't reach them, however nothing has changed on our end.

[AlexGG]

If you use a different tool, you may further damage your pool, and make recovery impossible.

All the specialized data recovery tools I know are read-only, with the exception of sometimes modifying partition tables. One can try every available software in turn and it is perfectly safe unless there is a mechanical problem. If there is a mechanical problem with the drive, repeated attempts to read it are likely to degrade the drive further, often to the point of irretrievable failure. This is normally solved by making a clone or a disk image of any drive which is mechanically suspect, as is strongly indicated in this case. Cloning comes with its own risk, though, sometimes people mess up source and target definitions, which is fatal. Data recovery shops often have green and red SATA connectors to try and prevent this error by simple "red means bad" rule.

From the data recovery point of view, the repeated attempts to roll back the pool are more damaging, because they change something on the pool, and with a broken filesystem you don't always know what it is. Especially when people sit and watch it try to roll back for three days straight. There is much opportunity to write over something useful during a three-day I/O intensive evolution.

In the case of stripes, if the drive is just recently added, it is not a stripe really, because there is no automatic rebalancing (nor manual rebalancing for that matter). So the old data still sits on the old (good) drive, presumably. That obviously depends how "recent" is the "recently added" drive, in terms of the filesystem age (which is not quite the same as the wall clock age, but instead is defined mostly by how much was written).