Resolving a Removed Device

If a device is completely removed from the system, ZFS detects that the device cannot be opened and places it in the REMOVED state. Depending on the data replication level of the pool, this removal might or might not result in the entire pool becoming unavailable. If one disk in a mirrored or RAID-Z device is removed, the pool continues to be accessible. A pool might become UNAVAIL, which means no data is accessible until the device is reattached, under the following conditions:

If a redundant storage pool device is accidentally removed and reinserted, then you can just clear the device error, in most cases. For example:

$ zpool clear system1 c1t1d0