It matters, RAID just keeps disk data safe. Alt-F is not installed on disk, nor its settings (except for disk-installable packages)
And regarding resync: it uses a lot of memory, and the 323 only has 64MB of RAM memory. There are several programs and scripts in the net (and one published by me in this forum) that splits rsync working into several sequential tasks, precisely to lower its memory requirements.
What I think it happens is that rsync consumed main memory, then started using swap, and when swap exhausted the system crashed.
resync memory requirements increase linearly with the number of files.
Can you perform the same jobs, in the same conditions, using the vendor firmware? If you can't you shouldn't compare apples and oranges.