I’m not sure you can calculate it. The usual approach is to make sure that PS has the largest and fastest drive to play with. What good would the calculation actually do you?
Dennis,
You need to have around 10 times the size of scratch of the largest file size (size in memory, not on disk), that you will be working with.
For most folks, a 2gig primary scratch is usually sufficient with a secondary set for any occasional ‘overflow’
Colin:
The reason I wanted to know is so that I could create a separate partition solely for use as a scratch disk. no point in making it much larger than necessary.
Len:
Thank you for the info. I will set up a 2.5 G for the scratch drive, and then set the secondary scratch drive to one of my other partitions on the same physical drive.
Slightly OT, but any suggestions on a size for a separate partition to hold the XP operating system, plus any other files which like to be on the C drive?
The idea here would be to be able to format the drive with the operating system when the inevitable reinstall becomes necessary without having to reinstall all of my programs.
There is no point in using different partitions on the same physical drive – all you end up doing is making the drive work harder as it zips between partitions.
The value in moving the scratch file comes from using a different physical disk.
Also, although putting your OS in a seperate partition to your applications has some merit, if you re-install the OS, odds are that any applications will need to be re-installed, to ensure that the hooks into various spplication data folders, and registry entries are correctly set up.
Dennis,
any suggestions on a size for a separate partition to hold the XP
operating system, plus any other files which like to be on the C drive?<<
At least 5gigs! More and more data is being added to the \documents & settings\~username\ folder with every new application release (and Microsoft says that is where all this data should go, so we can’t blame the apllication vendors).
For example, that’s where the Photoshop file browser cache gets created, and the more folders you run the file browser on, the more space that will take.
I have found that Photoshop CS appears to use much bigger scratch files than PS7. Also PS7 was limited to 2GB files so occasionally created two or more files per session. I donΒt know the maximum limit for CS (4gB?) but when editing 100MB images with only a few layers I have seen PS generate a 2.6GB scratch file. I currently have an 8GB partition on a separate fast SCSI drive for the scratch disk.
how big should a scratch disk be if using 50mb 16bit files? would it slow down the (separate internal drive) to partition it?
thanks!
Ideally your scratch disk should be on a different physical drive to that containing the OS. This is to prevent slow-downs caused by Photoshop’s Scratch and Windows’ paging file competing for read/write time.
Partitioning does not do the same thing.
In practise this gets more important as you work on very big multi layered files and/or have several open at the same time.
Go for as much scratch space as you can. HD space is cheap these days. What many do is purchase a new large capacity HD for the OS, programs and data, then put the old one into service as a dedicated scratch disk.
Hope this helps.
Chris.
Thanx Chris,
Is 250 gb an overkill? i meant partitioning the scratch disk (ie getting a 350 gb disk and partitioning some for backup and the rest for scratch.
Yes that would be okay. Have the first partition on the disk (the fastest) set to Scratch. (Mine is 20GB FWIW).
If the rest of the disk is just used for back up and archive, you’ll experience no read/write conflicts whilst you are working.
Chris, so you use 20 gb…how big are your ps files? I don’t want to allocate more space than needed for scratch, i’d rather use it for backup…
It can be a tricky area in general but if your computer can accommodate SATAs they seem the way to go.
In a three disk system:
#1 – OS and programs
#2 – user data
#3 – scratch disk and as suggested backup data.
in a four disk system similar to above with Windows virtual memory assigned to the fourth platter.
In vista it looks as if the above can be restructured a bit as Vista manages (or seems to manage) VM in a different way.
Rather than a mega second drive I’d suggest a three drive system but four drives (platters) is or seems to be a better optimum in my opinion.
I just want to know how many gigs the scratch disk should be…
Confused?
Don’t mind Deebs, it’s his speciality! He often talks a lot of sense – but rarely about the subject in hand π
so you use 20 gb…how big are your ps files?
The way PS works – and the only way it can work with very large files – you could consider the Scratch disk to be acting as Memory with the physical RAM acting as a cache for that memory.
It’s not just the file size you need to consider. Each layer can add considerably to Scratch usage as can each history step and each snapshot.
The higher the Cache Settings (EDIT>PREFERENCES>MEMORY & IMAGE CACHE) the more memory will be consumed as Photoshop keeps a copy of the screen image at all the various zoom settings to speed up redraw time.
The thumbnails in the Layers and Channels palettes all take up memory. You’ve then only got to start having several 16 bit images open at once to really consume a serious amount of scratch space.
Trust me. It’s better to have too much than too little.
Chris.
thanks chris! can you be more specific? would 100 gb be an overkill?
spphoto,
Chris is a pundit in the forum and he knows what he’s talking about. He has what I would call the ideal set up for his scratch disk on a non RAID system. So following his advice you won’t go wrong.
That said, one can overmanage the scratch disk, trying to eek out every bit of performance possible. In general, depending who you are and the type of demands you place on your computer, the extra 80% of effort isn’t worth the 20% gain.
Oh, I know, there are some who would argue that it’s not that difficult to optimize performance, but until you get your arms around photoshop, unless you’re having a specific problem, just put your 350 gig in and let photoshop manage the space it needs. Until you get to about 40% fragmented, or about 60% full, you’re not likely to notice any difference. And when you do, you’ll be in a better position to judge any performance gains by the work that you do.
If you plan on it being just an extra drive, set your Primary Scratch disk to it, and the secondary to C.
The biggest factor is the amount of free contiguous disk space. That means, the less your HD becomes fragmented, the better for the scratch disk performance.
Given that you have a Raptor for your second drive, where the scratch files will live, I wouldn’t bother with a separate partition. Just defrag occasionaly.
thanx guys!
I would prefer to take a partition from the scratch disk and use it for backup.
I guess i’ll have to defragment often.
I guess i’ll have to defragment often.
Not necessarily. It depends on the work that you do and your expectations of PS performance. You may find it to be a non-issue. On the other hand, if it does become an issue, there are ways to optimize.
LOL @ post #7 π
Perhaps I should explain?
There are two main ways to "paint"
One is to paint each object in turn – a linear sort of process
The other is to provide sufficient background detail for another individual to fill in the foreground details as they see best.
I, of course, am often tempted by option two π
Oh, before I forget – I’d be tempted not to partition a drive and prefer platters over partitions any day.
