Hi,
I'm facing the same issue with SC 4.5.
We try to restore 11T DB to an alternate host. There are 3,5T restored in 5 hours.
I tested the read performance, it's possible to do 450MB/s. The storage system is running at 5%.
SATA cluster, physical DB host with 2x16G FC.
I don't see any traffic on the LUNs, don't know how the data are copied.