11 Replies Latest reply: Apr 10, 2009 6:05 AM by P_Shock RSS

    Is having a "scratch drive" still advantageous w. new computers?

    RichPate Community Member

      I use to see it mentioned quite often that having a scratch hard drive, in addition to the drive that PS is running from, speeds up edit processing of large image files. In regard to today's fast multi-core processors, hard drives and bus speeds, is this still true?

       

      Anyone using a scratch drive on a new computer? Thanks.

        • 1. Re: Is having a "scratch drive" still advantageous w. new computers?
          Ramón G Castañeda Community Member

          Rich_Pate wrote:

           

          I use to see it mentioned quite often that having a scratch hard drive, in addition to the drive that PS is running from, speeds up edit processing of large image files. In regard to today's fast multi-core processors, hard drives and bus speeds, is this still true?

           

          Anyone using a scratch drive on a new computer? Thanks.

           

           

           

           

          But of course!

           

          It has absolutely nothing to do with the CPU, multi-core processors, drives or buses.

           

          Photoshop always uses a scratch disk.  The very instant you open an existing document or create a new one, the scratch disk is created.*  If you do not have another separate drive designated as your primary scratch disk, then the scratch disk will be created by default on your boot up volume, where Photoshop's scratch disk will be competing with the OS swap files for the use of the only set of read/write heads.

           

          My primary scratch disk is a dedicated, physically separate 160GB internal hard drive.

           

          * The scratch disk is created by Photoshop based on calculations of your customary workflow, the size of the document, the number of layers, etc.  Figure on 35 to 50 times the size of your largest file ever, or more.  This is not limited to "large" image files.

          • 2. Re: Is having a "scratch drive" still advantageous w. new computers?
            RichPate Community Member

            Thanks Ramon. OK, that's what I thought.

             

            Is it also true that your scratch disk needs to be as fast as the boot drive PS is on? Let's say, if your main application/OS drive is a 7200rpm, 16mb cache SATA drive and your designated scratch drive is a USB external 7200rpm, 16mb cache SATA drive, would it be best to keep the boot drive as the scratch disk?

            • 3. Re: Is having a "scratch drive" still advantageous w. new computers?
              Ramón G Castañeda Community Member

              Rich_Pate wrote:


              would it be best to keep the boot drive as the scratch disk?

               

               

              Never —in my opinion.

              • 4. Re: Is having a "scratch drive" still advantageous w. new computers?
                SaturnV CommunityMVP

                Rich, if you're looking for performance on a new Mac, then you'll want to think of it like this:

                 

                Your first priority is to load the new machine with as much RAM as you can afford. Once you have a few GB past 4GB, then Photoshop will let Mac OS X automatically store your scratch data in high RAM. This is your first priority because RAM is much faster than any disk. You can now put 8GB RAM on Mac Pros, iMacs, and some MacBook Pros.

                 

                Whether or not you can do that, you still need to get the fastest disk or RAID you can find that is never your boot disk and assign that as your scratch disk. Even if you already have a lot of RAM, a scratch disk is still needed for when your image editing overloads the RAM you have.

                 

                With a scratch disk, it isn't a matter of making up the difference between scratch disk and the boot disk. It's only a matter of making up the difference between the speed of the scratch disk vs. the speed of RAM.

                • 5. Re: Is having a "scratch drive" still advantageous w. new computers?
                  Community Member

                  You never want scratch on the boot drive which is why laptops and iMacs are not the best choice for Photoshop.

                   

                  Photoshop will always write a scratch file even if you max out your RAM. By putting the scratch on a second drive the read/write heads are not fighting over writing scratch and SWAP files which slows down the computer.

                  • 6. Re: Is having a "scratch drive" still advantageous w. new computers?
                    Chris Cox Adobe Employee

                    Unless you have 4 exabytes of RAM - yes, a scratch disk (or multiple disks) is a BIG advantage.

                     

                    As long as you want to edit documents larger than RAM, or keep history states larger than RAM, or keep lots of presets larger than RAM, etc. -- we need the scratch disk system. And the OS VM system just isn't designed to handle data like that (across multiple disks, with non-MRU access patterns).

                    • 7. Re: Is having a "scratch drive" still advantageous w. new computers?
                      RichPate Community Member

                      Thanks everyone. Well, here is my situation and the method of my madness.

                       

                      My G4 PowerMac died, so I got a new Mac Mini (all I could afford) with the RAM maxed out at 4GB. Instead of continuing to run the Mac version of Photoshop Elements 6.0, I have sold most of my fun possessions to by a used (legal) version of Photoshop CS3.

                       

                      For a scratch disk, I have the option of using a USB external SATA drive OR to hack my Mini and move my DVD drive to an external enclosure and replace it with a 2.5" SATA internal hard drive. Using an external hard drive would be easier, but it sounds like going with an internal hard drive that's independent of the boot drive is the best way to go for a scratch drive.

                       

                      So my last remaining concern is whether or not the hack would be worth it relative to better performance in editing large mult-layered HDR image files?

                      • 8. Re: Is having a "scratch drive" still advantageous w. new computers?
                        P_Shock Community Member

                        Just get an external FireWire (400) drive and use that as your scratch disk. It will be much faster than using USB. Of course, if you already have the USB drive and don't want to spend more money, USB will work too!

                         

                        -phil

                        • 9. Re: Is having a "scratch drive" still advantageous w. new computers?
                          RichPate Community Member

                          P_Shock wrote:

                           

                          Just get an external FireWire (400) drive and use that as your scratch disk. It will be much faster than using USB. Of course, if you already have the USB drive and don't want to spend more money, USB will work too!

                           

                          -phil

                          Thanks Phil. Unfortunatly the new Mac Mini no longer has a Firewire 400 port, but instead, a FW800 port. I have discovered that FW800 enclosures are expensive and rather hard to find.

                           

                          I thought that USB 2.0 was a bit faster than FW400? Is this not true -- with USB having 480 somethings/sec vs. 400 for FW400?

                          • 10. Re: Is having a "scratch drive" still advantageous w. new computers?
                            Ramón G Castañeda Community Member

                            Rich_Pate wrote:

                             

                             

                            I thought that USB 2.0 was a bit faster than FW400? Is this not true --

                             

                            Not the way USB 2 is implemented on the Mac.  FireWire is better.

                            • 11. Re: Is having a "scratch drive" still advantageous w. new computers?
                              P_Shock Community Member
                              Unfortunatly the new Mac Mini no longer has a Firewire 400 port, but instead, a FW800 port.

                              Sorry, I didn't realize you were using the new Mini.

                               

                              But that's even better - FW 800 will be faster than FW 400. USB is theoretically faster but that doesn't hold in real world use. USB is designed for quick bursts of small amounts of data - Firewire has been proven far better for sustained transfers for larger amounts of data (like a scratch file). For backing up files where time isn't so much an issue, USB is fine, but for Photoshop scratch disk use, you want the fastest drive possible.

                               

                              Firewire 800 drives are a bit more expensive but they provide better performance. You can find decent deals on them if you shop (I recently purchased a Western Digital 2TB RAID that included FW800 for $230) They're not hard to find either if you know where to look.

                               

                              http://eshop.macsales.com/shop/firewire/1394/USB/EliteAL/eSATA_FW800_FW400_USB

                               

                              Alternatively, if you want to use a FW400 drive with your Mini, FW400 adapters are cheap.

                               

                              http://eshop.macsales.com/item/Sonnet%20Technology/FAD824/

                               

                              -phil