Need a First Aid utility


From one day to the next, the bootloader greeted me with

```
ZFS i/o error - all block copies unavailable
LUA ERROR: memory allocation error: block too big.

can't load 'kernel'
```

This teaches me a couple of things:

* To increase robustness of the system, we need some real r/o base system
* We need a **Backup** utility even though we have snapshots and BEs and whatnot. Stuff can still fail if the entire pool or the drive fails
* We need a **Disk First Aid** utility (and it needs to run from the Live system). If helloSystem is going to be used by "mere mortals", then this will be needed no matter how easy the Backup utility is...