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best PS CS3 scratch disk

C

ChrisA

macrumors G5
Jan 5, 2006
12,581
1,695
Redondo Beach, California
jtblueberry said:
What would be best for a scratch disk?
1. 150GB 10k Raptor http://www.newegg.com/Product/Product.aspx?Item=N82E16822136011
2. 36GB 10k Raptor http://www.newegg.com/Product/Product.aspx?Item=N82E16822136054
3. One of the above but with 2 drive in RAID 0
4. Other
Please take into consideration cost and how much space is needed for scratch.
Click to expand...

Does PS even use the scratch disk? Moderd system have so much RAM that I doubt the disk is even used much or even at all. ack in the day a large image could not fit inside RAM so many of the "tiles" went to the disk but the other day I had two 300MB image files both open at the same time and they both fit inside RAM.

Open up Activity Monitor and watch the disk as you work. If the scratch disk is not being used then yo don't need a fast one.
 
J

jtblueberry

macrumors regular
Original poster
Dec 20, 2007
111
0
Pismo Beach, CA
ChrisA said:
Does PS even use the scratch disk? Moderd system have so much RAM that I doubt the disk is even used much or even at all. ack in the day a large image could not fit inside RAM so many of the "tiles" went to the disk but the other day I had two 300MB image files both open at the same time and they both fit inside RAM.

Open up Activity Monitor and watch the disk as you work. If the scratch disk is not being used then yo don't need a fast one.
Click to expand...

I'm glad you said that because it more clearly defines my question. I was surprised to find that photoshop is consistently gobbling up all 14GB of ram on my new mac pro. I figure getting a fast scratch disk would be the best thing I can do to speed things up even more. I do a lot of batch actions and picture packages. It's not uncommon to open up 50 full resolution 5D images at a time in my workflow. Anyway, the 2.8 octo flies through things but I'm looking to make things as fast as possible while I'm going through the upgrade.

I'm leaning toward two 36GB raptors in a RAID 0 array. I think that should be plenty of space and would give me that fastest speed possible...right?
 
B

bocomo

macrumors 6502
Jun 29, 2007
495
0
New York
photoshop goes to scratch disk once it runs out of ram so scratch disk is still important

in photoshop you can go to preferences in the info palette and set it to display scratch sizes. that way you can see for yourself if/how much you need
:)
 
C

ChrisA

macrumors G5
Jan 5, 2006
12,581
1,695
Redondo Beach, California
compuwar said:
RAID will slow things down. If all you're using it for is scratch, then RAID isn't really going to gain you anything.
Click to expand...

RAID-0 is an exception. It really is faster. With RAID-0 two drives are "zippered". so that if the RAID volume were just a list of sectors numbered 1, 2, 3, 4... the the odd sectors are physically stored on drive A and even sectors on B. RAID-0 can be twice as fast.

The problem with RAID-0 is that if either drive fails you loose all of the data on both drives. So while twice as fast it is twice as likely to fail. But for a scratch drive we don't care much if the data are lost. The biggest users of these RAID-0 systems are video editors. Still images do not stress the drive much

Other RAID levels store data redundantly which is always slower to write but some times slightly fester to read. But RAID-0 is no redundantly
 
compuwar

compuwar

macrumors 601
Oct 5, 2006
4,717
2
Northern/Central VA
ChrisA said:
RAID-0 is an exception. It really is faster.
Click to expand...

RAID 0 can be an exception, if it's hardware RAID (or software on an external system,) then striping over two drives is going to be much faster- with OSX-based software RAID, the main CPU has to do the checksumming/parity thing while it's doing whatever main task it's already doing. Whenever my PS is going out to scratch, it's because I'm doing something pretty CPU intensive as well as memory intensive, so I'm not sure you're going to see better performance under load with software striping. With no load, sure, you'll see ~2x of write and read delta with software RAID.

It'd sure be an interesting benchmark though- every "test this RAID" benchmark I've seen with OSX has the CPU somewhere between 75-99% just running the benchmark.
 
J

jtblueberry

macrumors regular
Original poster
Dec 20, 2007
111
0
Pismo Beach, CA
Yeah. I'm curious to know if the OSX software RAID 0 would show an improvement because I know it uses the processors. However, I have noticed I quickly use all ram (14GB) and hit the scratch disk but I'm never over 50% processor usage. I think it would be faster to use two drives striped but I just don't know.
Again I have Dual 2.8 Quad Core (early 2008).
I'd love to see some kind of memory intensive benchmark between a 7200rpm vs 7200rpm striped vs 10k vs 10k striped.
 
J

jtblueberry

macrumors regular
Original poster
Dec 20, 2007
111
0
Pismo Beach, CA
I just did some tests for some common things in my workflow.
I couldn't find any speed difference when using a 1tb seagate 7200.11(new and unused) vs the 500gb seagate 7200.10 boot drive that came with my computer. I saw that at the scratch disk was getting used (about 4-6gb worth on each test). I thought I'd see a faster result from using the 7200.11.

I did find something interesting though. When I ran picture packages or a batch action on 25 files, they ran almost twice as fast if I clicked back to activity monitor or safari or any other program. If I stayed in Photoshop and watched the action run it took way longer. ie. 25 picture packages took 3min15sec to run if I stayed in photoshop but they only took 1min45sec to run if I clicked over to another application. I could even be doing something in another application and they would run faster. Weird huh?

The only thing I can think of is that the photoshop is trying harder to produce the image for you to see if you don't click away. Maybe the graphics card slows things down (I got the stock ATI HD 2600)?

I was borrowing the 7200.11 for scratch (it's really meant for backup). And, I still feel I need a dedicated scratch disk so that my other disks remain less fragmented and more pristine. I really wish I knew if the raptor and/or raid would be faster for me (by the way, my processors never went above 15% for these tests so software raid 0 should speed things up right?).

Anyway, it's nice to know a trick that doubles the speed of what I do for free!
 
compuwar

compuwar

macrumors 601
Oct 5, 2006
4,717
2
Northern/Central VA
jtblueberry said:
I did find something interesting though. When I ran picture packages or a batch action on 25 files, they ran almost twice as fast if I clicked back to activity monitor or safari or any other program. If I stayed in Photoshop and watched the action run it took way longer. ie. 25 picture packages took 3min15sec to run if I stayed in photoshop but they only took 1min45sec to run if I clicked over to another application. I could even be doing something in another application and they would run faster. Weird huh?
Click to expand...

It takes time to display data, the more data, the more time- I don't know if you remember the Win95 original folder copy animation taking much longer than a copy that didn't do that- MS decoupled the animation from the copy- but Adobe can't really do that with Photoshop because it's more WYSIWYG.

Not really all that strange IMO.
 
J

jtblueberry

macrumors regular
Original poster
Dec 20, 2007
111
0
Pismo Beach, CA
I'm thinking the raptors might not be worth the extra money for me. What would the cheapest, fastest, 7200rpm drive I could get? I think 80GB would be plenty.
I can find a WD caviar SE16 250 GB for $70.
Are there any drives that would work better for less?
 
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