The below information is extracted from the smartctl man page.
To look at ATA disks behind 3ware SCSI RAID controllers:
smartctl -a -d 3ware,N /dev/sda
smartctl -a -d 3ware,N /dev/twe0
smartctl -a -d 3ware,N /dev/twa0
Where N is the disk number.
Devices /dev/sda and /dev/twe0 is used with 3ware series 6000, 7000, and 8000 controllers that use the 3x-xxxx driver.
/dev/sda form is deprecated starting with the Linux 2.6 kernel.
/dev/twa0 is used with 3ware 9000 series controllers, which use the 3w-9xxx driver.
You can also check on the series with the below command:
lspci |grep 3ware