Linux – LVM on RAID vs RAID on LVM: Which Is Better?

I would use rsync as it means that if it is interrupted for any reason, then you can restart it easily with very little cost. And being rsync, it can even restart part way through a large file. As others mention, it can exclude files easily. The simplest way to preserve most things is to use the -a flag – ‘archive.’ So:

rsync -a source dest

Although UID/GID and symlinks are preserved by -a (see -lpgo), your question implies you might want a full copy of the filesystem information; and -a doesn't include hard-links, extended attributes, or ACLs (on Linux) or the above nor resource forks (on OS X.) Thus, for a robust copy of a filesystem, you'll need to include those flags:

rsync -aHAX source dest # Linux
rsync -aHE source dest  # OS X

The default cp will start again, though the -u flag will "copy only when the SOURCE file is newer than the destination file or when the destination file is missing". And the -a (archive) flag will be recursive, not recopy files if you have to restart and preserve permissions. So:

cp -au source dest

My personal preference is always for hardware RAID but would use software over none. I am also aware there are some who have the opposing view. Yes, it will continue to function if one of the drives fail. That is the main reason to use RAID. The "R" stands for redundant.

Software RAID must impact performance because the CPU is having to do more. However, in reality if that difference becomes noticeable you're pushing the server far too hard, which will result in more problems than the loss of a few CPU cycles. e.g. Heat will become a serious concern.

One question I would ask is why such tiny drives? For very little more you can get much larger drives. If nothing else, 80GB drives are becoming quite hard to source, which may be an issue from the future maintenance point of view.