Hi,
i have a system with 3 hard disks connected to a USB2 box, which contains 3 hard disks of exactly the same type and i like to back up my data in the USB2 box. On one of the disks i have the "main" running partitions (boot, etc, usr, var, tmp) -dynamic data, while the other disks contain static data.
1/My question is if with both mdadm and sync -haven't decided which method to use yet- i can mirror everything including the "main" running partitions or i can only mirror the partitions, which contain the static data.
2/If yes, then wouldn't inconsistencies be caused? How can the running partition mirror itself?
3/I once wrote a script, run it as root and started erasing system data. Fortunately, i had backups and i restored successfully... mdadm seems interesting, but there is no way to protect me against such an incident -since the removal of data will immediately be mirrored-, isn't it? It seems like i must go with the sync tool. Suggestions about that?

Thanks

You need to separate the concepts of high availability (raid) and backups eg using rsync to another disk/tape/....