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Photoshop CS4 does NOT use RAM as scratch disk

Jan 17, 2012 4:27 AM

Photoshop CS4 does NOT use RAM as scratch disk

as far as I can tell.

 

I have 20 GB RAM and still Photoshop uses the hard disk as scratch disk.

(OS = Win 7 64).

 

Can I force the use of RAM as scratch disk?

 

/Larry

 
Replies
  • Currently Being Moderated
    Jan 17, 2012 10:11 AM   in reply to LarryM01

    Perfectly normal, expected behavior.

     

    Photoshop always uses a scratch disk, from the very instant you open an image file or create a new document.  Always.  No exceptions.

     

    See my reply to this other user's post:

     

    http://forums.adobe.com/message/4146851?tstart=0#4146851

     

     

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  • Currently Being Moderated
    Jan 17, 2012 10:16 AM   in reply to Tai Lao

    Hey, you're the "other" guy too!    You double posted.

     
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  • Currently Being Moderated
    Jan 17, 2012 11:16 AM   in reply to LarryM01

    The closest that you can get would be to create a RAM Disk, but think that, all things considered, you will be best off using a physical HDD, for Scratch Disks, and leaving your RAM for operations that do use RAM. That will allow for less use of Scratch Disks, and you might see an improvement, over having less RAM available. With fast and cheap (were cheaper, prior to the Taiwan floods) HDD's, RAM Disks are pretty much a thing of the past, or only really useful under certain circumstances.

     

    Good luck,

     

    Hunt

     
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  • Currently Being Moderated
    Jan 17, 2012 12:33 PM   in reply to Bill Hunt

    I normally figure 30 to 50 times or more the size of your largest file ever for the minimum size of your main scratch disk.  My dedicated, physically separate main scratch disk drive is 200 GB in size.  In comparison, any RAM disk would be utterly insignificant.

     

     

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  • Trevor Dennis
    5,922 posts
    May 24, 2010
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    Jan 17, 2012 1:01 PM   in reply to Tai Lao

    I've always bumped my scratch disk whenever updating my OS drive.  So I currently use a 150gb VelociRaptor that does nothing but PhotoShop scratch space - before that I used a 100Gb 7k2 drive for scratch, but that now sits on a shelf unused.  In fact the 150Gb v'raptore has survived two upgrades as I got a 300Gb VelociRaptor for OS the day Windows 7 was released.  That 300Gb v.raptor is now paired with a second one in a raid0 that has better sequential read/write times than my SSD OS drive.  This evolution approach is easy on the pocket, but you end up with a lot of different sized drives so you can't suddenly decide to raid them.

     
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  • Currently Being Moderated
    Jan 17, 2012 4:24 PM   in reply to Tai Lao

    Yes, I have 2x 500GB SATA II's, that sit for Scratch Disks, but they were set up, before retirement, when I did many high-rez triple-trucks and panos. Now, it's probably overkill for just my work, but have not bothered to change settings - besides, might do some big panos for myself?

     

    Hunt

     
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  • Noel Carboni
    23,514 posts
    Dec 23, 2006
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    Jan 17, 2012 5:44 PM   in reply to LarryM01

    I think Larry is responding to Adobe's claim that Photoshop will use RAM above 4 GB as scratch space.  Trouble is, I think that is outdated info.  I don't recall where I saw that claim, but it's definitely out there somewhere.

     

    The thing is, Photoshop CS4 has a true 64 bit app in the package, so you'll want to use that variant, Larry, to take the best advantage of your large RAM.  You can safely set your Photoshop RAM limit to even as high as 95% with 20 GB on tap.

     

    -Noel

     
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  • Currently Being Moderated
    Jan 17, 2012 10:47 PM   in reply to Noel Carboni

    I think the info still holds, but it was RAM used as a cache for the scratch disk.

     

    But of course that was only relevant for 32 bit Photoshop. With the 64 bit app it's moot.

     

    Either way, a scratch file is always created.

     
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  • Currently Being Moderated
    Jan 17, 2012 11:10 PM   in reply to twenty_one

    >> But of course that was only relevant for 32 bit Photoshop. With the 64 bit app it's moot.

     

    Nope, same still applies.  Only difference is 64 bit can use more RAM.

     
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  • Currently Being Moderated
    Jan 17, 2012 11:11 PM   in reply to Noel Carboni

    >> I think Larry is responding to Adobe's claim that Photoshop will use RAM above 4 GB as scratch space.  Trouble is, I think that is outdated info.

     

    Yes, that part is outdated for the 64 bit app.  It still holds for the 32 bit app.  And even with the OS caching, the sratch disk still gets used.

     
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  • Pierre Courtejoie
    7,038 posts
    Jan 11, 2006
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    Jan 18, 2012 5:02 AM   in reply to LarryM01

    "Yes, it is possible that Photoshop caches and uses RAM for scratch disk,  and then just also double saves to the hard drive as a safety measure."

    Photoshop does use the RAM as cache.

     

    "But why would Photoshop vaste CPU energy to do that?"

    Because the engineers tested it, and saw it gives the fastest results...

     

    "What's the proof that Phshp uses RAM as scratch disk?"

    The fact that you have the guy that wrote part of the code posting in the thread should be good enough...

    But if you don't believe him, make a test: search for a relevant Photoshop speed test. (not one that just uses radial blur, but some like retouchartist or macperformance guide large, or medium)  Run it. Time it. 

    Reduce the amount of RAM used by Photoshop in the preferences.Run the test, Time it.

    Remove some RAM, Run the test, time it.

     

    Or look at this: http://macperformanceguide.com/PhotoshopCS5-performance-vm.html

     
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  • Pierre Courtejoie
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    Jan 11, 2006
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    Jan 18, 2012 5:05 AM   in reply to Pierre Courtejoie

    If you want to have no paging on the hard drive, look for the maximum amount of memory you can install on your machine. Some use 16Gigs sticks, and up to 96Gigs of RAM (but I doubt that the speed bump would be worth the money invested.)

     
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  • Noel Carboni
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    Dec 23, 2006
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    Jan 18, 2012 7:28 AM   in reply to LarryM01

    Assuming you don't try to run several RAM hungry 64 bit apps simultaneously (i.e., when you're running Photoshop that's the one big app you're running) you can set Photoshop's RAM limit so as to leave just a gigabyte or so free for the OS.  With 16 GB of RAM I have my setting at 95% and never see problems.

     

    Thanks for clarifying, Chris.  I guess I just assume that anyone running a 64 bit OS would naturally be running the 64 bit build of Photoshop.

     

    Regarding Photoshop's scratch disk use, Larry, no matter HOW much RAM you have you want a fast scratch drive with hundreds of GB free.  That's practical experience talking.

     

    -Noel

     
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  • Pierre Courtejoie
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    Jan 11, 2006
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    Jan 18, 2012 7:57 AM   in reply to LarryM01

    "I don't see how testing the 'amount of RAM used by Photoshop' say anything about if scratch disking happens only on the hard disk OR in RAM and the hard disk.

    All you can see is that the hard disk is used as scratch disk."

    You would see when the hard disk is hit. If you could record an action with your common workflow, you would be able to see if everything fits into RAM.

    But I'm confused about the reason you are posting here: to understand how it works, or because hitting the hard disk brings unacceptable slowdowns in your workflow?

     
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  • Currently Being Moderated
    Jan 18, 2012 3:07 PM   in reply to LarryM01

    Under some circumstances a scratch file can really explode. I'd never use anything under 150 - 200GB.

     

    Most of the scratch activity is background anyway. You can hear the disk spin, but that doesn't mean it's slowing you down.

     
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  • Currently Being Moderated
    Jan 18, 2012 4:01 PM   in reply to LarryM01

    LarryM01 wrote:

     

    Everybody just seem to assume that Photoshop uses (some) parts of RAM as work space - I just need a better understanding of this. And some correct descriptions.

     

    Try reading this: Memory Allocation and Usage

    While based on Photoshop CS2, as far as I can see, it's still accurate (right Chris?)

     
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  • Currently Being Moderated
    Jan 18, 2012 5:11 PM   in reply to LarryM01

    LarryM01,

     

    Not until—and unless—computers with several hundreds of GB of built-in RAM became feasible, economically viable and commonplace, would Adobe programmers would remotely entertain the notion of providing an option for the user to bypass the Photoshop scratch disk and use RAM only.

     

    You have had the nature of the compulsory and ever-present scratch disk explained to you in detail, including by notable luminaries like gurus Chris Cox and Jeff Schewe, and others with admirable and seemingly inexhaustible patience.

     

    At this point, you are only taking this discussion to absurd extremes and wasting everybody's time.

     

    Just face reality as stated in post #1 of this thread:

     

    Perfectly normal, expected behavior.

     

    Photoshop always uses a scratch disk, from the very instant you open an image file or create a new document.  Always.  No exceptions.

     

    End of story.

     

     

    ____________

    Wo Tai Lao Le

    我太老了

     
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  • Currently Being Moderated
    Jan 18, 2012 5:21 PM   in reply to LarryM01

    A couple of additional  thoughts in parting:

     

    Photoshop moves stuff from the scratch disk to RAM and back all the time, as needed and as feasible.

     

    Additionally, if you think that nothing else is going on on your computer in regard to RAM and hard drive usage while working in Photoshop, just fire up the Activity Monitor and disabuse yourself of that misconception.

     

     

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    Wo Tai Lao Le

    我太老了

     
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  • Noel Carboni
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    Jan 18, 2012 5:21 PM   in reply to Tai Lao

    Ramon, you wrote:

     

    "Not until—and unless—computers with several hundreds of GB of built-in RAM became feasible, economically viable and commonplace, would Adobe programmers would remotely entertain the notion of providing an option for the user to bypass the Photoshop scratch disk and use RAM only."

     

    I don't mean to point out the obvious, but what happens when you just deconfigure all the scratch disks in the Edit - Preferences - Performance dialog, hm?

     

    -Noel

     
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  • Noel Carboni
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    Jan 18, 2012 5:28 PM   in reply to LarryM01

    Only you can determine how much RAM is needed for the other things you'll want running while using Photoshop.  The "ideal range" is just a loose guideline.  No OS itself is going to starve for RAM with 1+ GB available to it while PS is running.

     

    -Noel

     
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  • Noel Carboni
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    Jan 18, 2012 7:05 PM   in reply to Tai Lao

    I'm not where I can test that right now with Photoshop CS5, but that's not how it used to work.  It used to be (last I looked carefully, which was way back) that it would not use scratch space at all if no drive was selected, and I haven't read anything that suggests otherwise...  I'd love to hear Chris' thoughts on this.

     

    -Noel

     
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  • Currently Being Moderated
    Jan 18, 2012 7:35 PM   in reply to Noel Carboni

    Noel Carboni wrote:

     

    I'm not where I can test that right now with Photoshop CS5, but that's not how it used to work.  It used to be (last I looked carefully, which was way back) that it would not use scratch space at all if no drive was selected, and I haven't read anything that suggests otherwise...  I'd love to hear Chris' thoughts on this.

     

    -Noel

    I'm using CS5 on a Win7 Pro 64Bit system and you have to select a Scratch Disk.

     

    I currently have 5 drives in my system, 2x SSD's + 3x spinners, and on my system Photoshop defaulted to the C drive, the larger of my two SSD's, so I had to point it towards the second smaller SSD which I installed specifically for Photoshop.

     

    You can also select any, or all, of the drives in the system to be used as Scratch, and define the order in which they will be accessed. So for my system I have the SSD, plus a 1TB spinner, in that order, I've also given Photoshop access to 70% of the 16GB RAM I have installed; seems to be working fine!

     

    All the best

    Paul

     
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  • Noel Carboni
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    Jan 18, 2012 7:39 PM   in reply to pf22

    Thanks.  I'm on the road with an iPad and can't check Photoshop operation myself right now.  The last time I tried deconfiguring all the scratch disks entirely was back in PS 6 or 7 as best I can remember.  I did not realize that the configuration rules have changed.  Or maybe I just remembered wrongly.

     

    Whatever the case I don't much appreciate being called derogatory names by a forum member who chooses to be abusive after having been banned once from this very forum.  Take your attitude elsewhere, Ramon Castaneda aka Tai Lao.  It is not wanted here.

     

    -Noel

     
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  • Currently Being Moderated
    Jan 18, 2012 7:49 PM   in reply to pf22

    pf22 wrote:

     

    Noel Carboni wrote:

     

    I'm not where I can test that right now with Photoshop CS5, but that's not how it used to work.  It used to be (last I looked carefully, which was way back) that it would not use scratch space at all if no drive was selected…

     

    That is completely absurd and irrational.

     

    Photoshop will even return an error message and refuse to launch if the designated scratch disk is disconnected or otherwise not found.  If you do not explicitly designate a scratch disk volume, Photoshop's scratch disk file will transparently default to your boot volume, even if you don't see that inexorable fact reflected in your preferences.

     

    The above quote in pf22's post is all I see of N. Carboni's post, as I have now re-activated Greasemonkey and the afplonk! script, which had been temporarily and inadvertently disabled in Firefox.

     

    ____________

    Wo Tai Lao Le

    我太老了


     
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  • Currently Being Moderated
    Jan 18, 2012 7:51 PM   in reply to LarryM01

    Photoshop always uses a scratch disk, from the very instant you open an image file or create a new document.  Always.  No exceptions.

     
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  • Currently Being Moderated
    Jan 18, 2012 11:12 PM   in reply to Tai Lao

    A post of mine has been deleted from this thread—presumably by a bored forum bouncer with little else to do—which had been my reply to a comment by another poster to this effect:

    "I don't mean to point out the obvious, but what happens when you just deconfigure all the scratch disks in the Edit - Preferences - Performance dialog, hm?"

    The thrust of my deleted response was:

    Then Photoshop's scratch disk file defaults to your boot drive.  Oy!

     

    After that, I reactivated Greasemonkey and afplonk! and plonked the…user in question…again.

     

    It has never, ever been possible to prevent any version of Photoshop whatsoever from creating or using a scratch disk for every open document.  Any pretense to the contrary is a fallacy.

     

     

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  • Noel Carboni
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    Jan 19, 2012 10:08 AM   in reply to Tai Lao

    I apologize if I remembered wrongly about an ability to deconfigure the use of scratch drives.

     

    Ramon seems inordinately proud of his inability to interact politely with people on a public forum (and of employing special software to keep him away from others he doesn't know how to get along with), but I'm happy to be out of his sights.

     

    -Noel

     
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