D-Link DSN-5210-10 - xStack Storage Area Network Array Hard Drive Hardware Reference Manual page 12

High Availability (HA) Note: A system using a single controller (DSN-5110-10,
DSN-5210-10 or DSN-5410-10) and its expansion array(s) may use SAS or SATA
drives. A system using dual controllers for High Availability operation (DSN-
510 for the 5110-10, DSN-520 for the 5210-10 or DSN-540 for the 5410-10)
requires SAS drives be used in both the primary array and any expansion
array(s).
If you anticipate upgrading to HA with the addition of a second controller,
then it is recommended you install SAS drives.
4 Chapter 1 Introduction