Fastest Scratch Disk setup?

Right now, Photoshop can access 3 gigs of ram maximum. This might change in the future, but let's stay with the present.

Say you have 8 gigs of ram. You set photoshop to use 100% (which will be 3 gigs). You still have 5 gigs of ram.

OSX/Photoshop then use those remaining 5 gigs for scratch disk. So, if you have more than 3 gigs of ram, photoshop won't really touch the disk. I personally have 5 gigs of ram and I don't think I've touched my scratch disk (raid0) once. so it's sorta just sitting there.

If you are concerned with scratch and photoshop performace - get more ram. 8 gigs would be plenty.

To answer your specific question though - NEVER use a scratch disk that is being used for a system or apps. So your 2nd scenario is the best.

 

100% correct! Scratch disks MUST be formatted empty, dedicated and have no other apps assigned to use it, or performance WILL suffer.

However, as already stated, avoiding the SD entirely by having mucho ram is the far better way to increase PS performance

 

i hope you have a backup drive if you're keeping all of your files in a RAID0 array.

 

Not sure if this would make sense but this is how I have it set up on my main box which is a Vista64 machine (boo hiss) Anyway my setup is as follows which works for me.

Local Drives
-74GB 15K U320 SCSI drive (system, applications and PS scratch)
-36GB 15K U320 SCSI drive (system swap)
-120GB SATA (Games, work in progress)
-80GB SATA (System Images, temp space)

Network drives
-2x250GB SATA in network server for important data storage
-1x500GB SATA in network server as weekly backup of the 2 drives

Seems way overkill but stuff was cheap and plus I enjoy spreading the load amongst multiple spindles if I have to do video work while compressing files while in photoshop running some kind of batch convert then maybe jumping into a game while all that happens. I find when its off multiple disks, performance does not suffer at all.

 

I just use a dedicated formated 500 gig drive since I have 4 installed. I used to have raptors but they were too noisy.

You can also use an empty partition of your boot drive or some other internal drive in your machine. Unless you do hyper intensive processing you won't notice speed difference between a 7200 and a a 10k drive

 

I dont think using an empty partition on the same drive is any different than a scratch disk which is on a single partition system. Its still one spindle.

 

Nope. A scratch disk must be an entirely separate hard drive.