scratch disk numbers

[Caravaggio]

I am wondering what the 2 numbers mean in scratch in the info palette? Does the first number mean that 2.45G is being used and the second number that 11.1G is available? I thought that if the efficiency was 100% that the scratch disk wasn't being used at all. Thanks.

[John Wheeler]

Hi Michael (it is Michael right?)

Adobe is not always clear in its documentation and this is one of them. Here is the cut and paste from the help file for both of those items:

Scratch Sizes Information on the amount of RAM and the scratch disk used to process the image. The number on the left represents the amount of memory currently being used by the program to display all open images. The number on the right represents the total amount of RAM available for processing images.

Efficiency The percentage of time actually spent performing an operation instead of reading or writing to the scratch disk. If the value is below 100%, Photoshop is using the scratch disk and is therefore operating more slowly.

Here is the online link to the description all of their file/document information statistics:
http://help.adobe.com/en_US/photosho...b64-7508a.html

It is confusing because they mention scratch sizes which most often is associated with scratch disk. Their language in the description also mentions disk and then just RAM (Adobe did not write this up very well IMHO).

Here is my best understanding yet I am not positive. The right number is very close to the total allocated memory (RAM) as set in PS Preferences under Performance. I have seen this number change some while working with PS yet not much. The number of the left is the total amount of memory used for all open documents including the memory for all history states, clipboard, and undo buffer. If this left number is larger than the right number, then the excess is what is stored out on your scratch disk. This total memory number on the left of course includes all the Layers of each document. PS does some smart compression when it can to save on memory usage. Hope this helps.

ADDED: The 100% efficiency number means that the last operation ran totally in the Computer Ram and had no need to swap any information out to the Scratch Disk. When the left number approaches the right number is size, that is when you start using actual physical scratch disk and the efficiency number goes down from 100%

[Caravaggio]

Thanks, John for the explanation. That helps.

Michael