I have an Early 2008 Mac Pro (3,1) 2x 2.8 Ghz. I am currently using a 240 GB Mercury Accelsior PCI SSD as my boot drive (with OS X & applications) and triple RAID0 (with 3 750 GB Western Digital drives) as my Data drive (with docs, pictures, video, music). I have 18 GB of RAM.
I do a lot of photography work so I am looking to optimize performance in Lightroom and Photoshop. I also want a little more space on my Data drive.
I'm considering upgrading to a RAID0 with 2x 3 TB Seagate Barracuda (ST3000DM001), and then using the available 3rd bay for another 3 TB Barracuda I'd use for back-up.
Would this give me a significant performance improvement over the triple RAID0 I currently have?
keep the drives you currently have buy a pair of sata 2 ssd drives put them in raid 0 .. you will get way more speed then those 3 drives .. most sata3 ssd drives are backwards compatible so you shouldnt have any issue there mushkin chronos 120 gb drives are selling around 100 if you really want to spend the money OWC has great drives as well .. alternatively you could max out your system ram and create a ram drive that would be faster then your current raid setup but your storage capacity will be dependent on the amount of ram you have
The performance gains that you will see by replacing those hard drives depends on which hard drives you replace them with. The best performing 7200RPM platter drives available are members of the Western Digital Caviar Black lineup. I have a total of 6 of these in my system in two separate RAIDs. 2 1TB are internal and are connected via the Intel PCH. 4 2TB are in an external RAID enclosure and connected via eSATA. The 8TB external RAID nearly saturates the eSATA connection (SATA II) with read/write speeds approaching 300MBps. As advantageous as this may seem, I don't think that its a real help unless you're editing photos received from the Hubble Space Telescope.
Before you go about trying to improve performance in Photoshop and Lightroom, you should first figure out whether or not changing up your storage mediums will actually improve it at all. I can see how having a better storage backend would improve video editing, but I don't think that it would improve singular photo editing.