A minimum of one USB flash drive with the correct master access key is required to unlock  access to encrypted data after a system restart such as a system-wide restart or power loss.  No USB flash drive is required during a warm restart, such as a node exiting service mode or  a single node restart. The data center power-on procedure needs to ensure that USB flash  drives containing encryption keys are plugged into the storage system before it is powered  on. During power-on, insert USB flash drives into the USB ports on two supported canisters to  safeguard against failure of a node, node’s USB port, or USB flash drive during the power-on  procedure. To enable encryption by using USB flash drives as the only encryption key provider, complete  the following steps: 1. In the Enable Encryption wizard Welcome tab, select  USB flash drives  and click  Next , as  shown in Figure 13-24. Figure 13-24 Selecting USB flash drives in the Enable Encryption wizard 746  Implementing the IBM Storwize V5000 Gen2 with IBM Spectrum Virtualize V8.2.1