What is a scratch disk?

S
Posted By
sammybee
Feb 16, 2005
Views
352
Replies
12
Status
Closed
Hi all-

I’ve read the term "scratch disk" used on this forum many times but am not sure what it really is. I know what virtual memory is and know somewhat how it works with applications like Photoshop but don’t know how "scratch disks" work with it.

Any help would be much appreciated.

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B
Buko
Feb 16, 2005
Its virtual memory for photoshop.

a place to put the history states so you can go back and undo things.

It is best that the scratch disk be on a fast second hard drive.
DM
dave_milbut
Feb 16, 2005
I know what virtual memory is and know somewhat how it works with applications like Photoshop

the scratch disk in ps is different than with most apps. while most apps use ram first, then swap to a ‘scratch drive’ or ‘virtual memory’ on the disk when it runs out of ram, ps uses the scratch disk like other apps use primary memory. all the stuff it needs to store goes there. the real memory (on RAM chips) is used like ‘cache’ memory (like the kind on a processor chip) to speed up computing intensive operations.
ML
Mike_Logan
Feb 16, 2005
It is best that the scratch disk be on a fast second hard drive.

And how does one identify this scratch "disc" (aka scratch "memory" it seems) and place it on the second disc – if you’ve got one ?

Must say I get a bit confused when I’m working on a rather small file, nothing else is running in the background and PS tells me my scratch disc is full. I’ve got 512 RAM
DM
dave_milbut
Feb 16, 2005
And how does one identify this scratch "disc" (aka scratch "memory" it seems) and place it on the second disc – if you’ve got one ?

via your photoshop prefrences (edit> prefrences> memory and scratch disks)

Must say I get a bit confused when I’m working on a rather small file, nothing else is running in the background and PS tells me my scratch disc is full. I’ve got 512 RAM

go back and read post #2. 🙂
S
sammybee
Feb 16, 2005
Wow…thanks to you all for responding so quickly…

If I install another hard drive onto my laptop, say a 40MB hard drive, will Photoshop CS work faster? And, is the keyword "fast" hard drive as oppose to large capacity hard drive?
DM
dave_milbut
Feb 16, 2005
will Photoshop CS work faster?

probably not noticably unless the old drive was really REALLY slow or you work on huge files. You probably already know that a laptop isn’t the ideal platform for photoshop! 🙂

And, is the keyword "fast" hard drive as oppose to large capacity hard drive?

yes. fast as in RPMs. Slow ones are like 5200rpm, average ones are 7200RPM, fast can be 10 or 15000RPM and are usually only available as SCSI or SATA drives. I don’t think IDE can sustain rates that high.
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sammybee
Feb 16, 2005
Dave-

probably not noticably unless the old drive was really REALLY slow or you work on huge files. You probably already know that a laptop isn’t the ideal platform for photoshop!

Will I not notice the scratch disk performance-wise because I’m working on a laptop? Yeah…I have a laptop for customer presentations, initially, then I started to put everything on it.
DM
dave_milbut
Feb 16, 2005
Will I not notice the scratch disk performance-wise because I’m working on a laptop?

again, maybe, if the existing drive is a 5200 and you replace it with a 15000 and you work with really big files. adding ram helps too. if you’re upgrading, get as much as the laptop will hold, at the fastest speed it can handle (some systems can handle different memory speeds, some can’t, depends on your specific system).
S
sammybee
Feb 16, 2005
Dave-

Thank you very much on educating me on this.
SammyBee
DM
dave_milbut
Feb 16, 2005
no problem! 🙂
Y
YrbkMgr
Feb 16, 2005
Must say I get a bit confused when I’m working on a rather small file, nothing else is running in the background and PS tells me my scratch disc is full. I’ve got 512 RAM

In addition to Dave’s sage information, you get a "full scratch disk" message when you run out of disk space – it is important to clean out files from your temp folder regularly. Windows apps are supposed to remove themselves from the temp folder, but they often do not; at least not completely. So removing those files will free up space and reduce the liklihood that you will receive "full scratch dis" messages.
WK
William Kazak
Feb 19, 2005
Don’t forget to defragment your HD often. That really helps.

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