Is there such thing as hardware encrypted raid disk?

I have a server for which I want to protect the content. The server is located on a clients premises.

Is there a way to encrypt the content of a RAID DISK (at hardware level) ? What I need is that the server will not be able to start as long as the required password is not provided (the encryption key)

I will give the best answer to Miles, though the answer was not exactly to my question. But from all the comments, it seems that it cannot be done hardware or .. it cannot be done as I would like to.

Yes. You can encrypt a RAID volume, using TrueCrypt or any other whole-disk encryption software. The contents of the volume will be unreadable without the encryption key, regardless of who powers up the machine.

The traditional "benefit" of hardware encryption is added performance, not added security. Because many of today's high-end processors include support for hardware-assisted AES encryption, you are likely to experience similar (or perhaps even better) performance using software encryption.

Don't do this.

I'm in the process of trying to recover data from an encrypted RAID array that failed, and it's already cost my employer more than the data's worth. If you must encrypt, either encrypt individual disks, or create an encrypted partition for the important stuff.