Scratch disks

[Malcolm Tinn]

Hiya 

I have been using an other program successfully for my photo editing for many years and was pleased to be able to use the "scratch disks facility in preferences" to booster my computer power. Is there are will there be this facility in Affinity?  

[Callum]

Hi Malcolm Tinn,

Welcome to the forums

There is no feature like this I'm afraid however it has been requested in the past so it might be considered in the future.

Thanks

C

[Malcolm Tinn]

Callum

Thank you for your reply. At the moment I have gone back to using Photoshop on my PC because I find Affinity far too slow, I love it but too slow.

Scratch Disk may be the answer for me and others in this situation.

Best wishes
Malcolm

[IanSG]

14 hours ago, Malcolm Tinn said:

Scratch Disk may be the answer for me and others in this situation.

Does PS' performance slow down to the Affinity level when you disable the scratch disk option?  

[Malcolm Tinn]

IanSG the short answer is yes.

[R C-R]

44 minutes ago, IanSG said:

Does PS' performance slow down to the Affinity level when you disable the scratch disk option?  

Longer answer:

PS needs a fast scratch disk to maintain its performance because it can create huge numbers of 'scratch' items that have to be stored somewhere for as long as they are needed. For large documents with lots of layers these files require much more storage space than even a system crammed full with as much RAM as it can support, so they are offloaded either to VM (virtual memory) disk space under the control of the OS, or to one or more scratch disks designated in & controlled by PS itself.

If the scratch disk(s) & the interface(s) to them are faster than what the system can provide via its built-in VM management, then the performance boost is considerable. This also has the advantage, particularly important on systems with relatively small SSD's, of providing lots & lots of scratch space that does not have to be shared with system or other applications.

However, offloading anything to VM or even to very fast scratch drives is still much slower than if everything could be stored in RAM, so the Affinity approach is to minimize the amount of RAM required to edit documents to avoid that whole issue (& the expense of extra dedicated drives). But how well that works in the real world depends on several complex interrelated factors, including how much RAM other processes running at the same time on the computer need, how the OS prioritizes memory swaps with VM for all active & inactive processes, if & where a saved version of the document might be stored, & some other arcane stuff mostly related to the particulars of the OS, its memory management system, & how well (if at all) hardware GPU acceleration is implemented in the app itself.

So while there is no simple answer for this, currently the Affinity approach works much better on Macs than on Windows PCs. I know they are working on improving Windows version performance, & while scratch disks may be the way to go for them, it probably won't be as important for the Mac ones.

[IanSG]

I remember the many happy hours I spent learning VM management strategies for the VAX - and how little real effect it had!  Maybe I'll invest some time in learning about Windows' specifics.