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PaulDigney
Participant
February 3, 2017
Question

Scratch Disk Usage -Why?

  • February 3, 2017
  • 2 replies
  • 1373 views

Photoshop CC

windows 10

i 6700K  64 GB Ram

Photoshop set to use up to 44 GB

When opening a number of PSDs photoshop behaves well up to about 30 PSDs and uses around 30GB of memory.   Somewhere near that point it goes mad beating the scratch disk to death.   It slows down to a near stop, messes the overall performance of the system up.  After some minutes it is finished using the scratch disk so intensely and things work fine.  It is using about 15 gb of memory at this point.


I'm thinking about making the scratch disk an unused, old 128GB SSD I have or putting software in to create a RAM disk and let PS mess with that but I'd like to know why it needs it when there is lots of memory available.


Thanks,

Paul

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    2 replies

    Trevor.Dennis
    Community Expert
    Trevor.DennisCommunity Expert
    Community Expert
    February 3, 2017

    I so wish Chris Cox was still with Adobe and posting to this forum.  He'd have told us exactly what is happening with Paul's monster setup.  I have long suspected that Photoshop simply doesn't think in terms of making best use of 64Gb RAM, or even 32Gb, but arbitrarily assigns large temp files on the scratch drive, and then moves huge chunks of data  to and from the scratch drive(s).  As fast as an SSD is, 50Gb is still going to take several seconds.

    Paul, I'd be wary of that old 128Gb SSD.  I tried the same trick with the first SSD I ever had, but it was so much slower than a decent modern SSD, I changed my strategy.    I suspect that a system with 6700K and 64Gb will have at least one M.2 drive.  We have seen extraordinary read/write speeds with the latest M.2 drives.  In the region of 3.5Gb/s, so if you have such a drive and it has space, I'd try that.  With that sort of bandwidth, there is no reason why program files and temp files could not exist on the same drive.

    We could also make good use of our Noel in this thread.  He changed strategy a few years back, with six Samsung 256Gb PRO in a raid0, and used it for _everything_.

    Paul, as you have Windows 10, try watching the Resource Monitor (from the Task Manager Performance tab) and see if it is maxing out disk activity.

    P
    PaulDigneyAuthor
    Participant
    February 3, 2017

    Thank you all for such fast answers.  Let me try to respond to each all at once:

    It was using the performance monitor that enabled me to figure out that the scratch activity was my performance problem.

    I do have an M.2 drive.  It is my C: drive (550 GB).

    When the scratch disk was (by default ) on the C: drive it r e a l l y screwed the whole system for many minutes so even that isn't fast enough.  Certainly it isn't when the system is on the same drive.

    I'm just hoping the older SSD will be faster than any of my HDDs as a scratch disk to ameliorate the problem without any real cost.  I am thinking that haveing a smallish ( 5 to 10 GB) RAM disk as  scratch disk 1, then the SSD, then an HDD might be as good as I can do.

    Meanwhile I suspect this is yet another photoshop performance design flaw as Trevor suggests.

    It would be nice to have a way to tell photoshop to stay off the scratch drives if possible.  But since I don't know what it is doing with them I can't guess if this is a reasonable suggestion or not.

    To use RAM disk will cost a small amount for extra software and I haven't used one yet.

    To use the SSD  requires a card for more SATA ports and a cheap one didn't work at all so I'd have to go up market a bit.

    Meanwhile if I load the PSDs and walk away for awhile (like 15 minutes or so) when I come back the scratch drive has gone quiet and I can get to work.  I load the PSDs 20 to 40 at a time to run small actions on them (some are much bigger than others of course).

    Trevor.Dennis
    Community Expert
    Trevor.DennisCommunity Expert
    Community Expert
    February 4, 2017

    Paul would you mind raising this on the feedback site please?  As I said above, we used to have Chris Cox from the development team, who would see and take note.  Jeff Tranberry follows the feedback site, so there is at least a chance of it being addressed in a future update.  As things stand, am convinced Photoshop does not make best use of very powerful systems.

    Photoshop Family Customer Community

    Another place worth raising it is Puget Systems.  They don't have a forum, but they regularly carry out meaningful tests with Adobe software on high end hardware, and there might be a mechanism to ask a question.   Perhaps start an email with 'I am interested in buying your most expensive computer...' 

    https://www.pugetsystems.com/

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    February 3, 2017

    Photoshop can be a very resource hungry application.  Creating a RAM disk is not a good idea it Photoshop wants to use more ram its being use for scratch space. The SSD is the better choice for Photoshop scratch space.  Photoshop also does not return allocated resources till tou close down Photoshop.  Edit Purge items always seem to be grayed out these days. If I open a large Canvas and use filter surface blur it may allocate all my system ram 35GB of the 40GB I have.

    JJMack
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