hello, the topic is very old, but i hope someone still reads it. I was also very confused with this whole sata sas interposer thing. First i read on some forum that interposer can make sata look like sas to the system, therefore allowing SAS + SATA in RAID1 on the same virtual drive. WRONG!!! there is no way that could ever work. Then i read that the interposers are mandatory for the SATA drives to work on perc5i controler. WRONG again!!! SATA drives work with 2 different caddys without any interposer. So... interposers are no use for poweredge 2900 - 2950 what so ever! they are a waste of time. the only thing is... SATA are like 20x times slower then SAS drives.
Config: dell poweredge 2950 6 hdd bays
hdds: 2 seagate 1TB sas 7200k rpm vs. 2 seagate 1TB sata 7200k rpms
after setting them up in raid config utility at boot, the 4 hdds began mirroring.
SAS drives - 24% done
SATA - 4% done
Am i doing something wrong? or the sata drives are that slow... ?