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dedicated scratch disk

Michael Fontana

pro member
I'm going to update the Quad with the Jive, by Sonett. klick


Apart from a internal backup-HD, I'm looking for a dedicated scratch-disk for PS, APP and LZ.
As the Jive has 3 "slots" - minus one, which is taken by the internal backup - there's still place for another two discs.

My question: It's better to have a 74 GB-Raptor, with 10'000 rpm's, or to softraid - with disk utility - 2 slower ones for a RAID 0?

Point of view air conditioning, just a single disc for scratch would be better.

Thanks, Michael
PS. I know, that I need the PCI-E-card....
 

Asher Kelman

OPF Owner/Editor-in-Chief
I'd go for a single disk but keep it clean and empty.

You don't need a raid unless you have a combination of little memory and huge files and intensive disk accessing which slows you down. So are you waitng for things to happen?

Using an older computer to batch process RAW files is another consideration to speed up work.

Asher
 

Michael Fontana

pro member
Thanks Asher

RAM is plenty arround, with 8 GB.
Does one can use scratch drives for different apps simultanouisly, or has one to close the no-runners?
The other day PS'scratch went to about 8 GB.....
 

Klaus Esser

pro member
Thanks Asher

RAM is plenty arround, with 8 GB.
Does one can use scratch drives for different apps simultanouisly, or has one to close the no-runners?
The other day PS'scratch went to about 8 GB.....

Hi Michael!

I also have 8GB in my G5. But even then a dedicated level 0 raid for scratch is good. But only a hardware raid - that means a 2-channel SATA or SCSI card with really fast drives.
Because OS X is a Unix, it´s always scratching - no matter the amount of RAM.
For i´m doing video- and audioediting also, i prefer scsi drives at level 0 raid - they have similar read/write-speeds.
But for just working with photographs or 3D anim serial-ata raid with the internal 2channel does fine.

You can use one scratch for all - but i would suggest to make a dedicated partition for each application which needs fast scratch.

best, Klaus
 

Michael Fontana

pro member
Klaus

partitioning the scratches is a good idea, thanks
I don't feel a need for SCSI-RAIDs, hardware-based.

The rest is more tricky, as you wrote:
>raid with the internal 2channel does fine.<

doesn't works, as the PCIE-card for the Jive (Sonett) isnt bootable. Therefore the OS has to be on one of the original-ones. (Not the Sonett) So, here's the previous set-up:

Internal, actual: Raptor for OS, only + 500 GB for data.

Internal, future: Raptor for OS, only + 500 GB for data. & Jive with databackup + 1 scratch for imaging apps

Now: the 1 scratch for imaging could be

- a softraid 0, . done with disc utility, 2 smaller HD's, 3 partitions.
- or a 300 single GIG-disk, with 16 MB cache, 3 partitions.

I think the 2nd solution should be fine, as for writing/reading a 16 MB cache is a plus.
 
My thought would be:

As a scratch disk is literally a RAM replacement, which means when RAM is not available anymore, PS utilizes scratch discs.

Therefor, the faster the read/write and access time the better.

I would go for a hardware raid-o with 2x Raptor discs.

That's the approach I am driving at the moment. YMMV and I am on PC not MAC. Things might be different.
 

Michael Fontana

pro member
George,
AFAIK PS writes scrach in any case, well that's what Scott Byer, from Adobe is saying in its PS-forum.
I can't link, as some older links are broken, as they changed them, somehow.

But here's a statement from Bruce Fraser, I copied a while ago, from that forum:

"Bruce Fraser - 3:57pm Mar 30, 06 PST (#3 of 17)
As Pierre said, Photoshop only uses RAM as a cache for the scratch disk. It looks in the cache first, and if it finds what it needs in the cache, it doesn't have to go out to the hard disk to read. But if you pay attention, you'll notice that Photoshop is always writing to the scratch disk in the background.

Photoshop is pretty smart about the way it uses RAM as a cache—it tries to anticipate what you're likely to need, and stores it there. But if you jump back 30 states in nonlinear History, for example, Photoshop will probably need to consult the scratch file on the hard drive."

If you observ the size of scratch;you can see, that it goes to 20 - 40 GB, depending on the filesize, and the amount of time you keep PS running.

I wasn't aware yet, of S-ATA-RAIDs for PCI-E & mac, but Atto has one, for 1'000 $....
 
Last edited:

Ray West

New member
Well, not necessarily cheap, but I guess pretty fast would be compact flash. You can get it such that it will stand more read/write cycles than the ones we normally use, and you can get small pcbs (about 30$) that take two cf cards, and you use instead of 2 1/2 hdd, say. So you could software raid a few to get 40 gb. scratch disk, or get a more dedicated unit to take more cf cards. cf interface is more or less ide, so not a lot of electronics involved.

Best wishes,

Ray
 

Klaus Esser

pro member
Well, not necessarily cheap, but I guess pretty fast would be compact flash. You can get it such that it will stand more read/write cycles than the ones we normally use, and you can get small pcbs (about 30$) that take two cf cards, and you use instead of 2 1/2 hdd, say. So you could software raid a few to get 40 gb. scratch disk, or get a more dedicated unit to take more cf cards. cf interface is more or less ide, so not a lot of electronics involved.

Best wishes,

Ray

Hi!

My experiences are, that PS gains speed dramaticly up to 4GB RAM, than with 8GBRAM (which i have) not adds speed so dramatically.
With history-steps up to 40 and working on a 500MB-file and some layers (wich is average when with working LF on drum-scans), PS need to scratch.
Important is - as it is with most "heavy" programs - to have an own partition or, better, an own empty and fast drive, ideally a raid 0. Interaction between RAM and scratch should be as fast and broadband as possible.

best, Klaus
 

Ray West

New member
Hi Klaus,

In case you did not catch what I was saying, I was suggesting using cf as the scratch disk. I think it may be faster than a hdd, but it interfaces the same.

Best wishes,

Ray
 
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