Is it possible to connect a hard drive to the XHA1 to record instead of the tapes?
or possibly recording to both tape and hard drive.

Yes it is .. check around the forum here, opinions vary but there are some great comments/mini reviews
and recommendations.

Cheers.

Some folks record to CF cards using devices such as the DataVideo DN-60.
Some use products such as the Firestore.
Tape does provide a reliable back-up and is low cost.

Is it possible to connect a hard drive to the XHA1 to record instead of the tapes?
or possibly recording to both tape and hard drive.

I use the Datavideo DN-60 (CompactFlash rather than hard drive); you can record to tape and CF simultaneously - in fact, it's slightly slicker that way with the DN-60 than to CF-only.

I went this way because it's the cheapest by quite a margin. Its limitation is the size of the CF card - obviously, genuine hard drives are a lot bigger

genuine hard drives are a lot bigger

Unless you use a sony hvr dr 60 like I do :) Paired with sony's smallest battery this is a very small and light weight solution for recording externally.

Been using it for 3 years now and that was my best investment I did, it's like the recorder was made for the canon, you get 2 red dots in the viewfinder indicating that you are recording to tape and to the recorder, I always record to both and if the tape runs out I just let the recorder continue when needed, I can even change tape while it's recording to the recorder but I loose a second or 2 when I press the record button again to start up he tape, but it's also possible to just record to the recorder only, even without any mini dv tape inside.
Only disadvantage is that it takes about 12 seconds from startup until you are able to record.
Also for continuous recordings there is no frame loss due to the size limitation for recording to the fat32 disc, there is a Sony utility that seamlessly joins all files again. Biggest advantage is the excellent powermanagment, I can fill up the entire disc (4,5 hour) with just one big Sony battery and still have enough to spare to offload it to the computer.

I"m selling this set up this year, it's been a great but it's time to move on.