From the docs:
Optional: Move the identity to the subfolder in the storage location
It’s not required, but could prevent the storagenode from start, if the mounted disk is inaccessible.
In the meanwhile there is this storage-dir-verification file. So I am wondering if the suggestion is still recommended.
It’s still a good idea since it will reduce points of failure. If you lose the HDD with the identity, your node is lost. Same with the data HDD, so best to keep both in the same place.
However you can easily backup the identity and if it gets lost, just copy the backup back and everything is fine. Furthermore it is also possible to only lose parts of a HDD.
But it is no longer required to prevent storagenode from start when the disk is inaccessible? For that the storage-dir-verification file is sufficient?
Yes, that file ensures both that the data is available and matches the identity used.