NAS devices - recommendations?

Solid State Drive, still expensive, seems to be perfect for the audio. It has no moving parts while the only limitation is number of writes to each sector - small with audio (mostly reads). It is also silent.

Bob, I use three standard 1TB Firewire drives - one in use and two backups. I store files in ALAC. The other mode of RAID, you mentioned - stripping used to increase speed (alternating data) doubles the risk. Wen one drive fails both are gone. Mirroring is better but in addition to virus susceptibility both can be damaged by controller failure. I use Firewire drives only because it frees main processor allowing me to use computer for other tasks (plus Firewire is native to Mac). It doesn't affect the sound in my wireless setup.