some of camera using SxS memory card format it as UDF file system.
and NVS2501 doesn't support it.
Password
Answer by Chris2013-04-27
Depends on Camera you use,
i.e.
XDCAM EX1/3 or Canon C300 formats SxS in FAT, compatible with all NVS models except NVS-1501 Please note, It's not recommended to use NVS2525A UDF Special with non-UDF formatted cards.
PMW-200 or 500, Arri Alexa format SxS card in UDF, compatible with NVS-2825 (or NVS-2525A UDF Special) only
PMW-5 or 55 format SxS card in exFAT, compatible with NVS-2825 only
P2HD formats P2 cards in FAT, compatible with NVS-2825/2525/2501/2500