Digital BW, The Print

I just wanted to second, and perhaps emphasize, what Nick says here 
about a striped set (RAID level 0). You will get considerably more 
speed out of Photoshop if you are using a dual channel PCI card 
(Adaptec makes a dual 320MB/sec SCSI card) that is connected to at 
least 1 drive per channel, and then formatted as one very fast drive. 
The drives should all be identical and run at 10K RPM or better. 
Ideally, if you have the funds, a hardware-controlled (takes the 
processor time off your computer's hands; not subject to crashes) RAID 
tower holding at least 4 drives with two inputs (to make use of the 
dual channel PCI card) will give you about the fastest throughput you 
can attain, short of fibre channel RAIDs such as Apple and others 
offer. The scratch file setup can be the weakest link, after processor 
speed, in attaining maximum efficiency. Using internal IDE or ATA 
drives is not very productive by comparison. There are actually RAID 
setups out there that process approx 3 GB per second...for a whole lot 
of money. They are meant more for real time online video editing, but 
Photoshop can also take advantage of this kind of system. You don't 
need terabytes of drive space, just lots of drives striped on two 
channels. I suppose you could use two dual channel cards, split to two 
separate arrays, and double your speed again, but that is probably 
beyond your needs. Some companies, such as Sonnet, make a dual channel 
Serial ATA (SATA) card that allows you to avoid SCSI 
obsolence/conflicts.

If you use a partition or two on a couple of disks for scratch files, 
the remainder of those drives should not be under intensive use. The 
drive should ideally be dedicated only to scratch files, and the 
remainder partition, if any, to "dead storage" of files unlikely to be 
accessed while you are in Photoshop.

That being said, in no way should work be saved or stored on a striped 
array. Only scratch files are truly appropriate, because if one drive 
happens to fail, the scratch files on the array are toast. Using 
striped arrays therefore makes it imperative that you save your work 
frequently. Most I/T people prefer RAID 5 -- which requires at least 3 
drives and becomes less expensive per GB with more drives within the 
array...5 drives makes a good setup, with a 6th held in waiting to 
replace any drive that fails -- or better for this reason. This setup 
provides speed and safety. Some people like 4 drive setups where two 
drives are set to RAID 0 (striping) and the other two are set to RAID 1 
(mirroring). This is the most economical approach, but not quite as 
good as a RAID 5 setup.

My 2¢ from years of occasionally painful, but mostly satisfactory, 
experience.

Gary

>    Date: Tue, 22 Mar 2005 20:30:52 -0000
>    From: "Nick H. Nugent" <nghin@...>
> Subject: Re: Puzzled by PS scratch drives
>
>
> Yes and no.
>
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Steve Kale
> <stevekale@b...> wrote:
>> I'm not a computer engineer but wouldn't it make sense for PS to be
>> able to access multiple scratch disks - at the same time? Seems
>> that there would not be many situations when more than one scratch
>> disk ... is helpful.
>
> Yes. Maybe someone who knows the inards of PS can tell whether PS
> accesses multiple scratch disks on a multiprocessor system. Ideally PS
> should be able to parallelize sub tasks for layer groups where
> possible (maybe it is already doing it). Perhaps with a striped set
> the need to access multiple drives (or partitions) is not that
> urgent.
>
>> ... (being the "media" drive where the .psd ideally resides)
>
> Ideally the scratch disk should at least be in a dedicated partition
> to avoid performance degradation due to drive fragmentation. It should
> have nothing except the scratch file. Once PS opens a file it works
> entirely off of its temporary image until it is saved (or reverted).
>
> --nick
>
>
http://homepage.mac.com/barnettart/BarnettArt_Artwork/PhotoAlbum2.html



41° 19' 15" N
74° 17' 09" W


[Non-text portions of this message have been removed]

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Gary Barnett 
<barnettart@m...> wrote:
The 
> drive should ideally be dedicated only to scratch files, and the 
> remainder partition, if any, to "dead storage" of files unlikely to 
be 
> accessed while you are in Photoshop.


I have a 32Gb WD Raptor (10,000rpm)as my scratch disk (and another 
for virtual memory (page file?)plus a 72Gb one for images that are 
being worked on (and backed up to an IDE device whren completed or 
after a working session). 

The 32 Gb drives are formatted with Fat 32.  I archive, weekly, data 
files from another machine(<2Gb)to the disk designated for the 
scratch file but would never open these data files (last time I 
checked they were not fragmented).  So I have appx 30 Gb of free 
space.  This is the only disk I have indicated for PS in 
preferences.  

When the 4Gb limit is reached, does PS 8 open a new scratch disk in 
this drive, or does it become confused as to what it should do or 
otherwise be inefficient?  Should I reformat the scratch disk to NTFS?

While posting, I would like to add a supplementary: writing files to 
the 72 Gb Raptor- which I do frequently during processing - takes a 
looong time, I guess well over a minute for a c. 1Gb 48 bit layered 
file.  Is this normal.  I had thought of buying another 72Gb Raptor 
and using Raid 0 but all the advice I have had so far is that the 
real write time advantage would be minimal.

I am using an Intel 3.2 GHz processor and 3Gb RAM with other IDE 
devices for storage.

Advice would be much apreciated.

Colin