Regarding RAID levels: 0+1 (disk striping and mirroring) is what we usually push for. It provides both high I/O performance and high reliability. Downside: you need double your disk (20 GB to provide 10GB of 0+1 storage). RAID level 5 (data and parity striping across disks) also gives high reliability and fast reads, but reduces write performance. It needs less "overhead" storage as well.