Photoshop scratch disk - which to use?

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Ozei

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At the moment Photoshop is set to use two internal drives as scratch disks - numbered 1 and 2 in the Preferences dialog.

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1 is a 120GB SSD and 2 is a 500GB 7200rpm hard drive. The SSD is C: drive, so it contains Windows and programmes.

The question is - should I leave things as is, or (due to the relatively small free space on the SSD) would I be better off using just the 500GB drive?

The following is part of the SSD advice on the Photoshop help page (link): "If your SSD doesn’t have much free space (the scratch file grows bigger than can fit on the SSD), add a secondary or tertiary hard disk. (Add it after the SSD.) Make sure that these disks are selected as scratch disks in the Performance pane of Preferences."

What the help page doesn't say is how/when Photoshop decides to switch over to scratch disk 2 - i.e. does it attempt to use all of the free space on scratch disk 1 first.
 
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I'd be inclined to put another SSD in - for scratch you only need a small one so it shouldnt cost much. (this assumes your computer can accomodate more than two drives of course - if it can't i'd move the hard drive to a caddy and use it externally)
 
big soft moose said:
I'd be inclined to put another SSD in - for scratch you only need a small one so it shouldnt cost much. (this assumes your computer can accomodate more than two drives of course - if it can't i'd move the hard drive to a caddy and use it externally)
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The 500GB (scratch disk 2) is only a 'dump' drive so it's not that important - I could move it to a caddy or elbow it altogether and put another SSD in.

neil_g said:
how much memory do you have?
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16GB (on Win7-64).
 
neil_g said:
i wouldnt worry too much then, adobe say you only use scratch when PS has run out of memory it can use.
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Even with 16GB of RAM I do get an 'out of memory' warning sometimes - usually if I'm editing very large .PSB files with a lot of layers, or if I try to run Capture NX2 at the same time as PS.

(CS6-64bit btw).
 
Ozei said:
The 500GB (scratch disk 2) is only a 'dump' drive so it's not that important - I could move it to a caddy or elbow it altogether and put another SSD in.
).
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So where is all your data ? Is it already stored externally ? ( I was expecting Programs and OS on the SSD, Storage on the HDD) - if the data is on the SSD move it to the HDD to free up space. Alternately if the HDD is surplus take it out and put it in a caddy for external storage and put a second SSD in for scratch purposes

Also are you ruinning a 64 bit OS ? If you are running 32 bit OS then you are essentially wasting 12GB odf Ram
 
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Ozei said:
Even with 16GB of RAM I do get an 'out of memory' warning sometimes - usually if I'm editing very large .PSB files with a lot of layers, or if I try to run Capture NX2 at the same time as PS.

(CS6-64bit btw).
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ouch.

id default to the SSD for scratch if you have the space to spare.
 
big soft moose said:
So where is all your data ? Is it already stored externally ? ........

Also are you ruinning a 64 bit OS ? ........
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There are 5 drives in the PC - one 120GB SSD / two 500GB HDDs / one 2TB HDD / one 4TB HDD. All non-pic data is on the 2TB and all image files are on the 4TB. There are two other backup drives in a caddy - one 2TB and one 4TB.

The OS is Win 7 64bit.

neil_g said:
id default to the SSD for scratch if you have the space to spare.
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Which SSD - C: drive, or a second (new) one?

The PC tower has 6 bays but one has a fan in it so there are 5 available for drives. To put a second SSD in I'd have to elbow one of the 500GB HDDs.
 
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I'd elbow the 500GB in that case - a scratch doesnt need 500GB and a second SSD will make for a lot quicker scratch

I'd set it to the new one then keep that empty for scratch purposes.
 
Also are we sure it is the memory thats the bottle neck ? a fast scratch won't help if the issue lies elsewhere (processing power for example)
 
big soft moose said:
I'd elbow the 500GB in that case - a scratch doesnt need 500GB and a second SSD will make for a lot quicker scratch

I'd set it to the new one then keep that empty for scratch purposes.
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That does make a lot of sense.

big soft moose said:
Also are we sure it is the memory thats the bottle neck ? a fast scratch won't help if the issue lies elsewhere (processing power for example)
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Well, all I know is the warning is always the same - i.e. 'out of memory'. It's most likely to happen with CS6 and NX2 running at the same time, rarely with CS6 on its own.

The CPU is reasonable, it's a quad core i5 2500K @ 3.3Ghz - I wouldn't have thought it's causing a bottleneck, would you?
 
i have my scratch disk setup on a second 120gig ssd ( OS and programs on 1st ssd ) all other drives are external usb 2 and 3 drives
the main reason for all other drives being external is to keep the heat down in the pc case

ssd drives a fairly cheap now a 120gig ssd as a scratch disk is not a bad way to go also setting up virtual memory to the second ssd helps a little
 
Ozei said:
Well, all I know is the warning is always the same - i.e. 'out of memory'. It's most likely to happen with CS6 and NX2 running at the same time, rarely with CS6 on its own.

The CPU is reasonable, it's a quad core i5 2500K @ 3.3Ghz - I wouldn't have thought it's causing a bottleneck, would you?
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Doubtful

Would those programs use the GPU ? (if they do insufficient on board memory could cause the issue)
 
big soft moose said:
....... Would those programs use the GPU ? (if they do insufficient on board memory could cause the issue)
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I don't know about NX2 but Photoshop does - help page info here.

This is the GPU settings box in PS - I think these are default settings, at least I don't remember touching them.

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My GPU is a Radeon HD6700 series with 1GB of onboard memory. I don't know whether that's enough if both programmes are using it?

cosmicma said:
...... ssd drives a fairly cheap now a 120gig ssd as a scratch disk is not a bad way to go also setting up virtual memory to the second ssd helps a little
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If I decide to go for a new SSD I'd probably get a 240GB and use it for C: drive, then use the existing 120GB as a scratch disk.

This is a reasonably priced 240GB SSD - Crucial M500 - I wonder how it compares to others of the same size.

Edit: Here's one with a much faster write speed (525MB/s vs 250MB/s) - OCZ Vertex 460 - but it's a lot more expensive than the Crucial.

As for setting up virtual memory, Adobe recommend setting the initial size to 1.5x the amount of installed RAM and the maximum size to 2x the initial size. I've got 16GB of RAM so that would give an initial size of 24GB and a maximum size of 48GB (both figures sound like a lot to me). The trouble is they don't say which drive to put it on - link.
 
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You don't need to remove a drive to fit a second SSD in (assuming the current 120G SSD is a 2.5" one). You just need a £2 adapter plate that converts a 3.5" drive bay to 2 x 2.5" mounts. Like this: http://www.ebuyer.com/483484-2-5-to-3-5-bracket-adaptor-metal-bracket25350eby Not up to date enough to suggest which SSD to get. My expectation is that if you are using it to host scratch data exclusively, PS will use a consistent write method. If you could find out how (what size chunks primarily) it writes its scratch data, you might be able to find the best SSD by selecting the closest benchmark and seeing which drives come out top...
 
arad85 said:
You don't need to remove a drive to fit a second SSD in (assuming the current 120G SSD is a 2.5" one). You just need a £2 adapter plate that converts a 3.5" drive bay to 2 x 2.5" mounts. Like this: http://www.ebuyer.com/483484-2-5-to-3-5-bracket-adaptor-metal-bracket25350eby
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That should work installation-wise, although I'd have to make a modification to get it to fit. My case uses these hot swap drive trays so the 2 x 2.5" adapter would have to be bolted to a tray. The real problem though is there isn't a spare SATA socket for the second SSD (the motherboard has 6 and they're all in use already). A port multiplier like this might do the trick but I don't think there's enough physical room for it.

arad85 said:
Not up to date enough to suggest which SSD to get. My expectation is that if you are using it to host scratch data exclusively, PS will use a consistent write method. If you could find out how (what size chunks primarily) it writes its scratch data, you might be able to find the best SSD by selecting the closest benchmark and seeing which drives come out top...
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I've found this page which says that Photoshop writes its scratch data in chunks of just over 100KB - http://www.josephholmes.com/news-fastphotoshop.html. He says the figure was confirmed by a Photoshop engineer. (Scroll to 1st paragraph in 'Addendum' section 1/2 way down the page).
 
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What's the max memory your motherboard can handle? You may be better off maxing to 32G if you can.

If you do go for another SSD (and you should be looking at 128kB writes as your performance measure) you need to make sure it is on a SATAIII port - even if that means moving one of the other disks to a HBA (don't go for the cheapo Startech ones, I use a pair of Adaptec 1430SA's, but you can only get the 1220SA new now which is a 2 port version).
 
arad85 said:
What's the max memory your motherboard can handle? You may be better off maxing to 32G if you can.
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The motherboard can handle a max of 32GB. At the moment it has 4 x 4GB sticks - i.e. two Corsair Vengeance 8GB packs. To change up to 32GB I'd have to ditch those and put in two of these Corsair Vengeance 16GB packs which would cost £270 (arrghh, almost twice as much as a 240GB OCZ Vertex 460). Is more RAM better than a fast SSD scratch disk?

arad85 said:
If you do go for another SSD (and you should be looking at 128kB writes as your performance measure) you need to make sure it is on a SATAIII port - even if that means moving one of the other disks to a HBA (don't go for the cheapo Startech ones, I use a pair of Adaptec 1430SA's, but you can only get the 1220SA new now which is a 2 port version).
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I'm not sure what you mean by the bit in blue type above. How do I pick an SSD that complies with 128KB writes?

I can't fit an Adaptec 1220SA - the only empty PCIe slot on the motherboard is being blocked by the whacking great heat sink on the graphics card.
 
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Mikesphotaes said:
RAM much better.
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Just found this test. He's timed Photoshop with increasing amounts of RAM, adding 4GB at each step. There's a huge leap in speed between 4GB and 16GB (a difference of 59 seconds) - but the increase between 16GB and 24GB (the highest he tested) is not as great (8 seconds). If he'd done the test with 32GB he'd probably have got it down to 30 or 31 seconds.
 
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Ozei said:
Just found this test. He's timed Photoshop with increasing amounts of RAM, adding 4GB at each step. There's a huge leap in speed between 4GB and 16GB (a difference of 59 seconds) - but the increase between 16GB and 24GB (the highest he tested) is not as great (8 seconds). If he'd done the test with 32GB he'd probably have got it down to 30 or 31 seconds.
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That's for his test. You could try the test yourself by taking 1 then 2 then 3 sticks out of your machine with a representative image from your workflow and see what the curve looks like. The problem is you are seeing out of memory with your workflow and images and using scratch disks. Unless you can find someone doing a test similar to your workflow and image size, the results won't represent your workflow. Whilst I understand the cost implications of going for 32G RAM, adding RAM may be the best step forward for you.

As to 128kB writes, this is just a benchmark that is available for some SSDs. Just because an SSD has a great peak performance, it may be that it doesn't do so well at 128kB writes (which is close to the 100kB writes you were saying PS does when writing to scratch disks). Most SSDs are pretty consistent with performance and there are very few benchmark sites out there. If you can find the information, this is the benchmark to look at in your case.
 
arad85 said:
That's for his test. You could try the test yourself by taking 1 then 2 then 3 sticks out of your machine with a representative image from your workflow and see what the curve looks like. The problem is you are seeing out of memory with your workflow and images and using scratch disks. Unless you can find someone doing a test similar to your workflow and image size, the results won't represent your workflow. Whilst I understand the cost implications of going for 32G RAM, adding RAM may be the best step forward for you.
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Before trying your stick test I've just been doing a different one - i.e. provoking an out of memory warning by running PS & NX2 at the same time and measuring the RAM usage via Process Explorer up to the point of crashing.

Here's the RAM usage with PS running one big 4.35GB psb file and NX2 running three nef files of 110MB each (330MB total).

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Both programmes together are using more than 15GB of RAM (out of the 16GB available) - but - NX2 is hogging nearly 5GB of that even though all three nef files combined are less than a tenth the size of the psb!! If I open a fourth nef in NX2 I get the out of memory warning and PS becomes unusable - it'll crash the PC completely if the fourth nef is large enough.

So it looks like you, Pete & Mike are right - I need 32GB to avoid this situation. I suppose I could sell the existing 16GB to reduce the £270 cost of four new 8GB sticks.

arad85 said:
As to 128kB writes, this is just a benchmark that is available for some SSDs. Just because an SSD has a great peak performance, it may be that it doesn't do so well at 128kB writes (which is close to the 100kB writes you were saying PS does when writing to scratch disks). Most SSDs are pretty consistent with performance and there are very few benchmark sites out there. If you can find the information, this is the benchmark to look at in your case.
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Re the red bits - is there a specific name for the '128KB write' benchmark test? (if there is I might find the info more easily).
 
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Ozei said:
The SSD comparison table half way down the page is quite interesting.
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Yup... just goes to show the different write performance (look at the different Samsung 840s for example).
 
arad85 said:
Yup... just goes to show the different write performance (look at the different Samsung 840s for example).
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Yes, I'd noticed how different their performances were.

Btw, I just realised I'm already up to the RAM limit for my version of Win7 (Home Premium) - I'd need to upgrade to Professional or Ultimate to make use of 32GB.
 
I don't know if I'm talking tosh or not, but wouldn't using a SSD as a scratch disk seriously degrade its lifespan, after all SSD only have a finite amount of write cycles. Curious to know as I'm currently speccing up a PC build and hadn't considered using an extra SSD drive for scratch.

Spec:
32GB KINGSTON HYPERX BEAST DUAL-DDR3 2400MHz X.M.P
480GB KINGSTON HYPERX 3K SSD
2 Tb WD Black Caviar HDD
1 Tb WD Black Caviar HDD

1 Tb WD External USB 3.0 Disk

It may be with my spec I won't need to worry about scratch disks.
 
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They do say that HDDs have a better lifespan than SSDs - but does anyone know of an SSD that's actually failed because it was written to too often?

Either way, I can't see how using an SSD as a scratch disk would be any worse than using it as C:drive. Adobe's advice for Photoshop scratch disks includes this paragraph:

"To gain the greatest benefit from an SSD, use it as the scratch disk. Using it as a scratch disk gives you significant performance improvements if you have images that don’t fit entirely in RAM. For example, swapping tiles between RAM and an SSD is much faster than swapping between RAM and a hard disk."

(Above quote is from here: http://helpx.adobe.com/photoshop/kb/optimize-performance-photoshop-cs4-cs5.html)

Techreport.com did an endurance test on a number of SSDs by bombarding them with writes - the last report was that they'd passed the 600 Terabyte mark. That's a heck of a lot of writes - e.g. the equivalent of 614,400 Photoshop files of 1GB each! See page 5 of this article http://techreport.com/review/24841/introducing-the-ssd-endurance-experiment.
 
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Always take backups and expect disks (whether SSD or HDD) to fail. I use SSDs for main user drives on my 2 laptops, my main workstation and my works laptop. In fact, 99% of my day to day stuff is on an SSD...
 
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