This is the method I would recommend.
I have BackupPC running on a dedicated machine using a 1 tb hard drive w/ 538gb used.
I shutdown the BackupPC server, reboot using Clonezilla, image the drive, reboot
@ 538gb it takes just over 4 hours to complete the process. Being this is a dedicated machine, I take it down in the am, back it up and return it to service. Normally, I do not run backups during the day so to not slow down my end users.
From: Timothy J Massey
Sent: Thursday, October 25, 2012 11:38 AM
To: General list for user discussion,questions and support
Subject: Re: [BackupPC-users] Any procedure for using 2 external harddrives
"Tyler J. Wagner"
<firstname.lastname@example.org> wrote on 10/25/2012 09:14:47 AM:
2) Exporting a single copy of a specific backup to a removable destination and moving that off-site. (Option 2 above). A variation of this would be to make the destination for the archive a remote filesystem already off-site, and there is no physical movement at all.