An OSD - Optical Storage Device - is a small, portable data storage unit, the equivalent of a disk. Commander Shepard often uses them to transfer data between computers. OSDs are a key item in upgrade kits. It was also used for storing commercial games, although this appears to have fallen out of use by 2185.
- Fist's OSD - Obtainable from Fist's office after the crime boss is confronted. It contains incriminating files about corruption on the Citadel, and is of particular interest to the reporter Emily Wong.
- Qui'in's OSD - Obtained from Lorik Qui'in if Shepard decides to help him. This OSD has an encryption key to access restricted data from Qui'in's computer regarding Administrator Anoleis' corruption.
- Benezia's OSD - Given to Shepard by Matriarch Benezia. It contains the coordinates for the Mu Relay, to be transferred to the SSV Normandy's navigation computer.
- Hossle's OSD - Obtained from Gavin Hossle at the skyway between Zhu's Hope and ExoGeni HQ if Shepard agrees to help him retrieve his data regarding weapon modifications.
- Kirosa Generational Archive - an OSD that contains the complete genetic lineage of the salarian Kirosa family, for use in high-level reproductive negotiations. It was lost during the chaos at the Dantius Towers on Illium.