Which hard drive/SSD configurations should I consider for a Mac Pro (2.66GHz Quad 2009 Mac Pro) optimized for photography (currently Photoshop CS4 and Lightroom 3). The Mac Performance Guide suggests: - OSX/apps: 1x fast SSD drive - User area/files: 2x high performance hard drives in RAID 0 (striped) - Time machine backup: 2x high performance hard drives in RAID 0 (striped) But what should be used as a scratch disk? A separate partition of the SSD drive? I suppose the backup drive would also suffice. I'm also concerned about using RAID 0 as that would mean a total failure if one drive fails, but then again having Time Machine do hourly backups (plus manual ones after large jobs in between) should be pretty safe. I guess I could choose RAID 1 (mirroring) for the backup drives as speed isn't critical here and that would mean two independant backups should one drive die, but then this drive would be no good for a scratch drive as well because of lower performance. What do you suggest I do?