zgdesign

Scratch Disk Raid Configuration

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Hello,

I recently put together a high-end digital imaging machine, primarily to edit very high resolution images on. The majority of the applications that I use is Photoshop. My motherboard is a AW8-MAX, with 1066 fsb, and a P4-3.73 Extreme processor, and 4gb of Mushkin 800mhz ram. I tweaked windows to allow Photoshop 3gb of ram, but unfortunately once it reaches 2.7gb, it starts to write to the scratch disk, which is currently the same disk as the OS is on. The MB has 2 SATA raid cards built in, and I currently have one Raid 5 setup, with 4 74gb Raptor drives. This is very slow, once Photoshop hits the ram capacity and starts to write to the scratch disks. I need this machine to be much faster in read/write speed.

My options are, to take 2 of the 4 raptor drives, and put them on the second raid card, and setup a RAID 0, to be strictly used for the pagefile, and for the Photoshop scratch disk.

My second option is to buy a 320 Raid PCI card, and get 2 U320 SCSI 15k drives, and setup a RAID 0 on that.

The question at hand is, am I really going to gain that much speed with the second option, considering the PCI limitations, or should I just stick with the 2 raptors on a RAID 0 setup?

Thanks for all your input!

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Just my $.02 but i have found in my experience that RAID5 doesnt have much worth in the world anymore. I have replaced it in most cases with a RAID 1+0 which would work nicely over 2 controllers. It doesnt have much in the way of proccessing overhead and should have much faster writes. That said i hear of some success of just selecting all remain disks(no RAID, just JBOD) to share the swap file and let windows manage it. I am not sure if you will find alot of support around here for RAID0. I don't do much in the way of photo editing, but i have several small business clients that are now happy owners of file/mail/database servers running RAID 1+0 arrays in place of RAID5.

Again, my experience may not apply here but its my $.02.

Regards,

Chicago

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Firstly, you may want to look into using Windows x64 as an OS to get full use of your memory. There may be driver issues with any peripherals you're using and check to see if your RAID card is supported.

Secondly the onboard RAID will most likley be the bottleneck until you upgrade to a dedicated RAID card with better RAID and XOR processing.

Thirdly you could add either a 36gb or 74 gb raptor for use as the scratch drive once and if the memory is at capacity and this will help the speed. I dont think you will benefit from a RAID 0 scratch disk. Perhaps better educated people can answer that.

Lastly IIRC the P4 3.73EE gets trounced by AMD processors at half the price in Content Creation, Photo/Video Editing. For the same price you should have gone with a single/dual core AMD system. I know its too late but consider that just a tiny barb from an AMD user. :)

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Also you didnt mention wether your OS/programs were located on the RAID 5 or on a seperate drive. I think ideally for your use you'd want...

1 74gb raptor for OS/Programs

1 36gb/74 gb raptor for swap/scratch drive

4 x ??? in a RAID 5 or 1/0 setup for storage and redundancy. I don't think you need Raptors necessarly for this setup since mostly hogh data throughput is needed and can be fulfilled with larger cheaper storage drives like Maxline IIIs.

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Right now I have the OS and scratch disk all on the RAID 5. The RAID 5 is partitioned into a 20gb for the OS, and the rest for storage and scratch disk. All 4 drives are 74gb raptors, on Sata Raid II 3G built into board. There is another Sata Raid 3G on the board, which will allow me only Raid 0 or 1.

I looked into upgrading to XP64, but we have lots of hardware which probably wont have the proper driver support, and I don't believe that Photoshop is 64bit compatible.

Also you didnt mention wether your OS/programs were located on the RAID 5 or on a seperate drive. I think ideally for your use you'd want...

1 74gb raptor for OS/Programs

1 36gb/74 gb raptor for swap/scratch drive

4 x ??? in a RAID 5 or 1/0 setup for storage and redundancy. I don't think you need Raptors necessarly for this setup since mostly hogh data throughput is needed and can be fulfilled with larger cheaper storage drives like Maxline IIIs.

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If you've got all of your system AND apps AND scratch disk on the same raid-5 array then no wonder you've got puke speed.

Raid 5 gives you some data reliability improvement when working with large volumes and some read speed increase but SLOW writes. Add to that you're reading and writing from the same array and it's no wonder you're seeing slow performance.

You dont' say the budget, but personally if you're doing photoshop seriously and you're time is important to you I'd buy a new raptor for boot, a second one for scratch and temp work files and keep your raid array for final writes and storage.

Other option would be to use any newer drive for the second drive and get quite a bit more storage with still a pickup in speed compared with what you have now.

If you get that boot and scratch off the raid5 you're going to see a big improvement!

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If it's possible, the scratch disk should always be isolated to an independent disk. Putting everything on that RAID is destroying your disk performance with unnecessary seeks. It's a terrible idea.

With four disks, the ideal Photoshop workstation setup is as follows:

1. OS/Apps.

2. Pagefile.

3. Scratchdisk.

4. Data.

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If you need a RAID, I would say to use 2 discs for a RAID-1 for your O/S & apps.

Use the other two discs as independent drives, either put the swap on one, and the Photoshop scratch file(s) on the other, or create two separate PS scratch files, one on each disc.

If you have 3-4GB RAM, do you need to have a Windows swap file?

I think 32 bit XP can only make use of 3GB of RAM. I guess you have PS configured to use 90% of available RAM, so that's why it swaps at 2.7GB.

Under these circumstances, PS is probably starving the rest of Windows / other apps of memory, so PS is having to do heavy traffic to the scratch files at the same time that Windows is hammering the swapfile.

As I say, try disabling the swapfile, and setting PS at say 75%. With a couple of dedicated scratch discs that might give best performance.

cheers, Martin

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