Working photographer needs help with hard drives and raid O decisions

Question

Hi new here and also new to Mac well almost new been 20 years since i had a mac. i have a Mac Pro Book and this led to ordering the MacPro since I am a working photographer i made a complete switch in platforms so i have some questions and such but I did place a order on Friday for a 2.66 4gbs of Ram , 2 500 gb hard drive and a 30 in monitor and of course the ATI 1900 XT card so yes i am waiting like many for that card.
I put initial 4gb of ram since running CS2 will at least take a max of 3gb's in the memory cache . i plan on getting 2gbs more from OWC since that seems to be the only 3rd party ram at the moment that is working correctly from reading some of the threads here. Having 6gbs is a no brainer really given the amount of Raw processing that i do along with PS work plus having e-mail and other apps open at the same time. The ram to me is the easy part although expensive . My biggest issue is what to do with the 2 hard drive slots and Raid O or not but I will start a thread on that. But i will have 6gbs total for now and the bottom line is you can never have enough ram still holds true.
Now on to my diliemma with hard drives. I did have a raid O scsi 10k rapture and and 10 k scratch on my Dell box and I am just not sure what to do here. i ordered the 2 500 gb hard drive and I may just put them on the storage side of things than get 2 WD 150gb 10 k Sata drives. Now i could Raid O them for 300 gb and get a performace boast that way or i could keep them seperate and put everything on 1 150 drive and ue the second for scratch only. What i don't know is what Mac perfers and what works better. Not worried so much about failure of drives, thats just life in the big city stuff and you just have backups. What i more worried about is performance versus a waste . seems to me that Raid O may not even be needed with these new Intel boxes with all the horsepower going on. Now the other think I notice is the WD 150gb 10 k drives are 1.5 and not 3.0 so is it really faster than the 7200 3.0 single hard drives. I read barefeats shoot out and it seems just getting the right drives in 7200 and Raid O them maybe the answer.
Okay i am not the biggest geek on the planet but I do know my stuff but this is a area that i look for more knowledge on this. So if i can get some sound advice in this area. i know there are many photographers out there like me pushing hundreds of images that could use the same advice. Now let's leave the money end out , folks sometimes think more with there wallet than what works best not that I am opposed to saving money but after spending over 7 k already on this system it becomes a moot point. LOL
www.guymancusophoto.com

Answer 1

Ok your question is if you should RAID O the two 150GB Raptors or not.
I think it was wise for you to get a couple of them for a boot drive with "Time Machine" coming in the next version of Mac OS X. The second drive would make a excellent bootable backup and eliminating downtime if a boot drive dies on you one morning.
In fact any boot drive cloning software that is Mac Intel ready now would do you good.
Now Barefeats has run some tests, and I can pretty much back up what they say from my own experience.
Mac OS X and apps can be helped only so much by a faster boot drive, and a single 10,000 RPM Raptor is enough, RAID O a pair is overkill.
If you install everything on the boot Raptor and keep your space hogging files (except iTunes) in new folders on another drive, even a 7,200 RPM 500GB, the two drives combined is faster as there is nearly no wait. Both drives can be accessed at the same time. Keeping the boot drive slim keeps the stylus (arm) moving as little as possible to get all the small reads/writes Mac OS X needs.
I RAID O-ed my boot drives because 74GB was the largest they had at the time, so combining them gave me speed and larger storage. I hardly use the speed, it only comes in handy if by rare chance I duplicate a 20GB folder, then I can do it in half the time of a 7,200 RPM drive.
Some of the drawbacks of a RAID O set, especially as a boot drive is that I have to auto-clone the whole set to a external drive regularly (I actually do a couple). Since the data path is separated with a RAID O, any drive failure results in total data loss.
So if you RAID O those 150GB Raptors, your going to have to clone 300GB to a external drive (or another internal) regularly, like once a week. This will take considerable time and you can't use the machine while the cloning process is going on. Sure auto-cloning software like DeJaVu can be used at night/weekends, but why bother cloning more than you have to for no big speed increase?
However if your messing with huge Photoshop files that spill over your CS2 3GB RAM limit (you need to have a "scratch" thats as fast as RAM), duplicating large files and other heavy duty drive work, then a boot RAID O will come in handy. Just remember your initial performance of 185 MB p/s will drop about 20-25% when those drives are 3/4 filled. Still 140 MB p/s is extremely good and a no worry situation.
What is worrysome is anything below 80MB p/s (I'm talking uncached 4K write speeds under X-Bench) with a new boot drive and then as time elaspes that boot drive gets filled up and loses half or more of it's inital speed. 30 MB p/s is really slow. Beachball H&LL.
http://www.barefeats.com/hard33b.html
Do Erase W/Zero in Disk Utility all new drives before laying data on them. Drives get subjected to shock which causes bad sectors on the drive. Driver software uses your data as a guinea pig to test the sectors (which you might not be able to recover the file). Zeroing does this without your data, rewriting the bad sector map so your writes are much improved, OS is more stable. etc.