What size external USB drive do I need?

Yes, or multiple smaller ones. Installing it on a PC, and backing up over the network is fastest (at least with a gigabit network).

Thanks for the reply.
So the ReadyNAS will automatically span the hard drives?

alanderego wrote:
Thanks for the reply. So the ReadyNAS will automatically span the hard drives?

No, it will not automatically span the USB drives. So if you were using frontview backup you'd need to use multiple backup jobs.

Though as mentioned, the backing up over the network is faster than directly connecting the USB drive.

Some ReadyNAS models won't recognize USB drives > 2 TB.

Thanks again, but the only thing is that I only have laptops with only 500GB of storage.
Can I work with this?
On a side note, Is there a way to check the progress of the backup?
I have been trying to backup 750GB share for the past 2 days.
Every night I get an error message "A previous run of backup job is still running. Check if that backup job has stalled, or you may need to adjust the backup interval to account for the amount of data you are backing up. [Job 001]", but under backup jobs it still says in progress.

Thanks,
Alan