TS-HTGL/R5

I have been attempting to restore a dead Terastation Pro II TS-HTGL/R5

After following all of Buffalo's recommendations with no success, I have resorted to restoring data from a linux server.

I have all the drives mounted in a Fedora Linux 10 server. I followed the howto for restoring the terastation using Linux. One of the drives has apparently failed and I can not assemble the array because it claims that the superblock of 2 of the drives is missing.

Basically: drives 0, 2, and 3 are supposedly good. Drive 1 has failed. When I run a

mdadm --assemble /dev/md0 /dev/sda1 /dev/sdc1 /dev/sdd1 I get a failure claiming that the superblock of /dev/sda1 or sometimes C or D could not be found or is in use.

Before I go ANY further, I would like to backup the 3 or 4 drives to a new set of drives using dd. Is this possible/recommended with a RAID 5 array to avoid losing any data?

Can I use dd with a set of raid drives?!?

Once I duplicate the drives, I will continue with my restore process using mdadm.

Thank you!