We have a CentOS 3 server with about 300GB of data on an ext2 filesystem that we need to mirror onto a new drive, which we're then going to pull out and put into a second server. A straight disk-to-disk copy (with rsync, tar, or "cp -a" doesn't much matter) manages about 75MB per minute, which would take almost three days, and the system gets very sluggish while such a copy is going on, so we can't afford to just let it run.
Is it possible, without loss of data, to convert the existing ext2 filesystem into a mirrored software RAID, then add the new drive as a second device and let rebuilding the RAID take care of making the copy? Even if this took more time, we've had good overall system performance with software RAIDs rebuilding in the background before, so it could run as long as necessary. We'd then need to be able to remove the second device from the RAID and either convert it back into a plain ext2 or put it into a similar software RAID in the destination machine.
Is this possible? Is there another plan that would make more sense?
Thanks in advance for suggestions.