On 24 April 2015 at 21:33, Russell Coker <russell@coker.com.au> wrote:

For as long as LUKS has been available commonly available CPUs have been able
to encrypt/decrypt significantly faster than disks can write/read. CPUs have
been increasing in speed at a greater rate than disks, so I really don't think
a pair of separately encrypted disks is going to take much CPU time.

I dispute this assertion,

1. I don't think it's necessarily true.. Benchmarks such as this one indicate average 20-50% performance loss on a 2014 core i7 ultrabook.
( http://www.phoronix.com/scan.php?page=article&item=ubuntu_1404_encryption&num=1 )

2. I think CPUs / chipsets that make their way into home servers have been increasing in performance per watt, but haven't steadily increased in performance. Especially when you look at the trend for NASes and file servers to feature power efficient Atom & AMD cpus (and ARM..) rather than quad cores, and for some manufacturers preferring dual core i7's now instead of quad core i7's for power / thermal efficiency in laptops..

I think the RAID suggestion is a good one for servers that already have RAID configured, but the rsync and set up crypto (on the LVM or RAID device rather than the disk device) is probably the better long term solution for performance / power efficiency / simplicity.

Going to use the rsync solution. Thanks everyone :)