A good idea, but there are easier ways to do the same task. The project cpos-recovery on Sourceforge does essentially the same task, but relliably and quickly. There are several ways that this kind of quick copy can be used: 1) back up to an alternate partition as a backup boot partition if you want your system to be bombproof. 2) make an installable tar file that can be quickly applied to many new systems. 3) create another partition of a different type, and copy your system to it (think ext4 to btrfs), with the assurance that the system will boot, and run, properly (given that grub supports that filesystem). 4) create an offsite backup of your working system in case of problems. These are all easily done with cpos-recovery, so check it out.

if you assumed a size of 3-5 MB for each song, and a 6 Mbit/sec connection (that is what they are selling you for broadband), then you would be allowed to download at most about 150 GB per month, and yet you would be paying for the capability to download about 1950 GB per month. 30,000 X 5 MB = 150 GB 86,400 sec/day X 30 = 2,592,000 sec/month 2,592,000 X 6 MBit/sec = 15,520 GBit/month / 8 = 1920 GB/month By my calculations, they are saying that they are selling a 600 Kbit/s connection, with a possible burst speed of 6 Mbit/s. Since I don't have a comcast account I cannot say what their customer agreement promises, but they should certainly be held accountable to their promises, and this doesn't appear to be anywhere close to a broadband data rate.