How to accelerate by partitioning drives & how to distribute data among 'em

Question

Dear forum,
I have read guide to storage acceleration and guides to phototoshop acceleration, but they always warn that the best solution depends on the work i do, the hardware i have, and the hardware i think i can afford to buy. I'm hoping that if i tell you what photoshop work i do, what hardware i have, and what hardware i'm intending to buy, you can tell me how to accelerate by partitioning my drives and how to distribute data among them. My biggest questions are about how big the volumes should be, and what should go on each volume. It sounds vague here, but I get more specific below:
THE PHOTOSHOP WORK I DO:
*wet-mount raw scans of 6x7 cm film using silverfast software on microtek artixscan 120tf 4000dpi scanner: resulting 16-bit TIFF file is typically 550 MB in size.
*working in Photoshop CS2 on same file, adding multiple layers makes file 1 GB to 1.4 GB in size
*my system's limitations show up most painfully when I OPEN a file (this can take five minutes) SAVE a file (this can take more than ten minutes!), when i FLATTEN the image's layers for printing (this can take 5 minutes), and when i CONVERT the file from 16-bit to 8-bit (this can take 5 minutes). most other operations in Ps CS2 are fast enough (not snappy, but fast enough) for me to stay with my current processor for the time being.
THE HARDWARE I HAVE:
*Power Mac G5 dual 1.8GHz, made in 2004, with only 4 slots for RAM (not 8 slots).
(I'm told this has quite limited bus speed, as compared with other dual-processor G5s, and that this hardware will not benefit much at all from adding a RAID array.)
*one internal seagate 80GB 7200rpm SATA drive. this is half-full (it has 39 GB on it): it holds my OS and my Users folder, but NOT my photoshop image files.
*one internal Western DIgital 400 GB 7200rpm SATA drive. this holds my photoshop image files, but not my user folder.(This WD drive turns out to cause the G5 to hang up occasionally, requiring a re-boot; to avoid this, i recently learned, i can connect it with a host card adapter [see below].)
*two 500 GB external firewire drives
*two 300GB external USB drives
*I have 2.25 GB of RAM, but I'm about to buy 2 more GB to max out at 4GB.
THE HARDWARE I'M INTENDING TO BUY:
*2GB of RAM, of course.
*two Hitachi T7K500 500 GB SATAII HD 16MB Cache 7200rpm drives to occupy both internal drive slots in the G5
*a 2-drive external enclosure to hold my old seagate 80GB drive and my old WD400GB drive.
*a seritek host card adaptor for connecting the external enclosure to the G5.
THE PLAN:
What follows is a combination of suggestions I have received about what I could do and my speculation about how I could do it. Please see my Questions, embedded in the lines below: I'd be very grateful for any amendments or directions you can offer on this topic.
Drive A: first newly internal Hitachi 500GB drive:
partition into 2 volumes:
first (faster) volume, "volume A1," of 100GB to hold OS and Users folder but NOT photoshop image files.
(Question: how much space should I leave free on volume A1 for optimum performance? is 50% free of 100GB optimal? is 60% free of 100GB better? Is 50% free of 150GB better still? or does that cut into the other volume's space too much (indirectly cutting into the space of "volume B1" on Drive B, which is to be the WorkDisk/ScratchDisk)?
second (slower) volume, "volume A2" of remainder GB (almost 400GB) as backup for 400GB "volume B1" of the OTHER internal Hitachi Drive, a.k.a. Drive B.
Drive B: second newly internal Hitachi 500GB drive:
partition into 2 volumes:
first (faster) volume, "volume B1" of almost 400GB as designated WorkDisk/ScratchDisk for large photoshop image files;
second (slower) partition "volume B2" (exactly 100GB) as backup for 100GB volume 1 (OS volume) of the OTHER internal Hitachi Drive, a.k.a. Drive A.
(Question: how much space should I leave free on this WorkDisk/ScratchDisk for optimum performance? is 50% free of almost 400GB optimal? is 60% free of almost 400GB better? Is 50% free of 300GB just as good, with the additional advantage of indirectly allowing "volume A1" on Drive A to be 150+GB?
Drive C: old Seagate 80GB drive, in external enclosure: disk designated for running the Photoshop Application? How would I set this up? any pitfalls to watch out for? should i partition this drive, or leave the whole thing for Photoshop? or is it better to run photoshop off Drive D?
Drive D: old WD 400 GB Drive: second scratch disk? Storage disk? Both storage and scratch disk? how large should an empty volume on this disk be in order to be useful as a scratch disk? volume 1 or volume 2? if i run the Photoshop Application off of this drive, how large should the volume for that be? should it be volume 1, the faster, outside volume, leaving volume 2 for scratch disk space? or vice versa?
External Firewire and USB drives: i guess i'll just use them for storage/archiving and extra backup? or am i much safer buying more SATAs and Enclosures? or are the external firewire and USB drives plenty safe (so long as i double-back up), since i'll only power them up for the data transfer, and then power them back down?
Given that the large Photoshop files are not in my User folder, does it matter whether i keep the User folder (with its MS Word docs and a bunch of PDFs and so on) on my OS volume, "volume A1"? would it speed things up when I'm using photoshop if i moved the Users folder to another drive? what if i'd like to play iTunes while also working on photoshop? my iTunes music folder (with all the song data) is already on an external firewire drive. but the iTunes Library and iTunes application are, of course, in my User folder, which is on the OS drive. would moving the Users folder to another drive make much difference when i use photoshop and iTunes simultaneously?
But I wonder whether it makes sense to be using volume A2 on Drive A as a backup drive: wouldn't it make more sense to back up my working files to two external drives that can be traded out, one on-site and one off-site, back and forth (not so convenient when one of the backup drives is internal!)? and after all, why would i devote a 400GB volume to the task of backing up another 400GB volume that will never be more than half full? I need to leave a WorkDisk/ScratchDisk half empty for efficient use, but i can back up that 200GB of working files on a 200GB volume, right? so for a backup drive, I might as well use a slow, inexpensive external USB drive that will only be tuned on for backup and will then stay powered off, a drive that's easily transportable on and off site, right? or am i misunderstanding something?
by the way, what backup software do you recommend for backing up back and forth between Drive A and Drive B? I've been using Carbon Cpy Cloner. do you recommend that? or something that does more archiving of progressive states of data?
Thank you for any help you can offer!
Sincerely,
Mark Woods
Dual 1.8 GHz PowerPC G5 (2.2), 512 KB L2 Cache per CPU, w/ 4 RAM slots   Mac OS X (10.3.9)   2.25 GB DDR SDRAM (2x128MB plus 2x1GB)

Answer 1

Crossposted: Re: How to use Oracle partitioning with JPA @OneToOne reference?