Exactly how a missing device is reattached depends on the device in question. If the device is a network-attached drive, connectivity to the network should be restored. If the device is a USB device or other removable media, it should be reattached to the system. If the device is a local disk, a controller might have failed such that the device is no longer visible to the system. In this case, the controller should be replaced, at which point the disks will again be available. Other problems can exist and depend on the type of hardware and its configuration. If a drive fails and it is no longer visible to the system, the device should be treated as a damaged device. Follow the procedures in Replacing or Repairing a Damaged Device.
A pool might be SUSPENDED if device connectivity is compromised. A SUSPENDED pool remains in the wait state until the device issue is resolved. For example:
# zpool status cybermen pool: cybermen state: SUSPENDED status: One or more devices are unavailable in response to IO failures. The pool is suspended. action: Make sure the affected devices are connected, then run 'zpool clear' or 'fmadm repaired'. see: http://www.sun.com/msg/ZFS-8000-HC scan: none requested config: NAME STATE READ WRITE CKSUM cybermen UNAVAIL 0 16 0 c8t3d0 UNAVAIL 0 0 0 c8t1d0 UNAVAIL 0 0 0
After device connectivity is restored, clear the pool or device errors.
# zpool clear cybermen
# fmadm repaired zfs://pool=name/vdev=guid