IBM System Storage DS3000 Programming Manual page 503

If the primary storage subsystem is recovered but is unreachable due to a link failure, a forced promotion
of the secondary logical drive will result in both the primary logical drive and the secondary logical drive
viewing themselves in the primary logical drive role (dual-primary condition). If this condition occurs,
the VolumeCopy in which the primary logical drive is participating is unaffected by the role change.
You can perform a role reversal by using the set remoteMirror command. (For information about the set
remoteMirror command, see "Set Remote Mirror" on page 3-233.)
v To change a secondary logical drive to a primary logical drive, use this command, which promotes the
selected secondary logical drive to become the primary logical drive of the remote mirror pair. Use this
command after a catastrophic failure has occurred.
set remoteMirror role=primary
v To change a primary logical drive to a secondary logical drive, use this command, which demotes the
selected primary logical drive to become the secondary logical drive. Use this command after a
catastrophic failure has occurred.
set remoteMirror role=secondary
Chapter 9. Using the VolumeCopy Premium Feature
9-11