What are these and what do they do?
The interposer adds a lot of functionality to the drive. The primary function of the interposer is redundant pathing. SATA has a single path, and SAS has a dual path. The interposer adds a second path for active active redundancy. It also allows the SATA drive to use the same signaling as a SAS.
The interposer will reduce spin-up delays, and there is improved error recovery and logging. It also adds the capability to assign the drive to multiple hosts.
The interposer is mainly needed when the drive is used in a storage appliance. You will get redundant path errors on our storage devices if you install a SATA drive without an interposer.
Figure 1: A sample represenation of an interposer board; multi-brand options that we stock at Tekmart Africa
NWCCG Dell 6TB 6G 7.2K 3.5 NL-SAS in F238F Caddy
M471A2K43CB1 Samsung 16GB DDR4 PC4-19200 (2400T) Notebook Memory
HP Genuine Proliant DL320 G3 G4 G5 DL360 G4 G5 G6 G7 Server Rack