IBM z13s Technical Manual page 567

Primary and alternate Support Elements fail
If the primary and the alternate SE both fail, the key cannot be served. If the devices are still
up, the key is still valid. If either or both SEs are recovered, the files holding the Flash
encryption key/authentication key can still be valid. This is true even in a key roll case. Both
new and current (old) keys need to be available until the key serving operation is complete.
If both SEs are down, and the Flash Express goes down and comes back online before the
SEs become available, all data on the Flash Express is lost. Reformatting is then necessary
when the device is started.
If both Flash Express devices are still started, get the primary SE back online as fast as
possible with the Flash encryption key/authentication key file and associated smart card still
intact. After that happens, the alternate SE can be brought online with a new smart card and
taken through the initialization procedure.
539
Appendix H. Flash Express