If you update from sarge to etch with an running 3dm2, please make sure if you use the default etch kernel (version 2.6.18) that you have installed the newest version of 3dm2.
If you use an old 3dm2 version with the etch kernel you get the following messages in dmesg:
3w-xxxx: SCSI_IOCTL_SEND_COMMAND deprecated, please update your 3ware tools.
3w-xxxx: SCSI_IOCTL_SEND_COMMAND deprecated, please update your 3ware tools.
You can get the newest version of 3dm2
here.