If the datastore does not appear in esxcfg-volume -l , the next step is scanning for VMFS headers:
esxcfg-volume -M <uuid_of_datastore> or force a mount if necessary: recover vmfs 6 datastore
vim-cmd hostsvc/datastore/attach <datastore_id> VMFS 6 stores a backup partition table and file system metadata in the first 1 MB and last 1 MB of the device. Even if the main partition table is lost, ESXi can often rediscover the volume using these backup structures. If the datastore does not appear in esxcfg-volume