Photoshop Scratch Disk...
Mike Lane
Registered Users Posts: 7,106 Major grins
I recall reading somewhere in the past 4 to 6 months about a way that you could hack photoshop to be able to use an external hard drive as the scratch disk. But now I can't find it anywhere.
So does anyone know how to do this? I've got an HP with a personal media drive with is essentially a USB2 harddrive and I want that to be PS's scratch drive to get it off the startup drive's back.
So does anyone know how to do this? I've got an HP with a personal media drive with is essentially a USB2 harddrive and I want that to be PS's scratch drive to get it off the startup drive's back.
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Is there a reason that you can't go to Edit/Preferences/Plug-ins and Scratch disks and simply select the USB drive as your primary scratch disk?
A few links where other people are talking about external scratch disks:
http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00DVhj
http://www.pcclub.com/forum/messageview.cfm?catid=33&threadid=17424
http://luminous-landscape.com/forum/lofiversion/index.php/t9070.html
http://www.quepublishing.com/articles/article.asp?p=30656&seqNum=2&rl=1
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7200 RPM and USB2 is 480MB/sec. Shouldn't be an issue.
http://photos.mikelanestudios.com/
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I was going to replace my PowerBook hard disk with a larger unit, but after looking at the difficulty of the chore I have decided to use an external drive instead. Since there is no performance hit worth worrying about this seems an ideal solution for me.
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Had that prob myself last night trying to extract rom a missing drive..but icon was still in MY comouter...somehow I unplugged the usb cable....
I did this on my Titanium Powerbook, and it was pretty easy. I replaced my 60 with the then biggest I could stuff in, 80. I then bought a self-powered enclosure for the 60, and it makes a handy-dandy portable drive. It's actually now my main photo disk.
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480Mb (megabits)
not
480MB (megabytes)
big difference.
480Mb/sec = approx 57MB/sec
Considering 7200rpm HD's come in around 50MB/sec you shouldn't notice a difference.....unless you're going from a SCSI HD to the USB HD.
Ahh valid point. I don't know what my main drive is, but I suspect it's not a SATA drive which would have made it up to 150MB per second... um I think
I actually went in and bought a SATA 150MB/s drive and went to install it in the computer only to find out that there is no extra drive bay. Gee thanks HP. So I got the (more expensive) HP personal media drive instead and I got another gig of ram. You wouldn't believe how difficult it is to install that extra ram. My big fat hands almost couldn't get to the connectors at all.
Here's another question about photoshop. What are its RAM limits for a single 32bit processor? I can go up to 4 gigs in my computer, but I don't want to if photoshop can't handle it.
http://photos.mikelanestudios.com/
Check out this article: Photoshop CS2- How much RAM. The short answer is OSX 3+ GB. Windows XP 2GB, 3GB in some circumstances. But, having more than 2GB can be advantageous because the rest of the system will use it and speed up other operations (like disk operations). My take on the article is that you continue to see speed gains on some operations by adding up to 4GB. Worth reading the article.
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the max transfer of the SATA protocol is 150MB/s....you'll still only get ~50MB/s out of the HD itself unless you bump up to a WD Raptor or some other super high speed (expensive) HD....and even then you wont get to the SATA limit.
Not odd at all. What you are observing is actually the way it does work, according to various "shootouts" available on the Web.
USB requires control by the host CPU. If the CPU is busy, USB might have to get in line.
FireWire is not so "Soviet"... it does not require central CPU control. It's capable of peer-to-peer. That and other architectural details give it higher actual throughput than USB 2.0.
Example-
http://www.usb-ware.com/firewire-vs-usb.htm
So let's talk RAID then. I know there are various forms of RAID and I've seen home desktops that allow RAID 0 and 1, one being performance and one being data security - which I'm sure you know very well. So how much of a performance boost can one expect with a performance RAID setup?
http://photos.mikelanestudios.com/
RAID 0 = Striping (performance)
different blocks of data written to different drives
RAID 1 = Mirrored (data security)
same data written to both drives
there are others, but not worth worrying about for this application.
With a RAID 0, i would guess a 30% overall performance increase. I say overall because things like file copying would be in the neighborhood of 50% but other things like application startup may see minimal or no increase. It all depends on the application. I have no idea how photoshop would be affected.
Keep in mind though with a RAID 0 if you lose one drive you're done and by adding another drive into the mix you've effectively doubled your chances for losing a drive.
Whereas if you go to a 2 drive RAID 1 setup, you've cut your chances of losing data in half or probably more (I'm not smart enough to figure out probabilities).
You could do a RAID 0+1 which is striping + mirroring, which would get you near the performance of a RAID 0 with data security but you'd need a minimum of 4 HD's to swing it. Then you have to start worrying about power, heat, noise etc...
I have a co-worker who runs 0+1 at home. We run RAID 1 on our workstations here at the office. FWIW I don't run any RAID config on my home PC.
That's the same exact logic that some kind of big wig at the FAA used to say that no engines would be safer than 4 engines on a 747.
It's also the same logic that (correctly) says that aircraft that have 2 engines are more reliable and most cost effective than aircraft with 3 or 4 engines. Which is why almost all of the new big commercial aircraft out there have 2 engines.
And I digress...
http://photos.mikelanestudios.com/
Assuming some basic sanity (when a drive fails, fix it asap) then it is actually better than that...
odds of data loss approaches odds of drive 0 failing * odds of drive 1 failing
So it's exponential, not linear.
If you have 4 drives to play with, you might as well go raid 5. You'll get some of the same performance boost to reads (unless you buy hardware raid, writes will be penalized, so don't use this for scratch... but when you come back later to find some image, the speed boost is nice.) plus you'll get data integrity on par with a two drive raid 1 (two disks have to fail to loose data) AND you'll get more usable space than you will with a 4 drive 0+1 (or 1+0) config.
Alternately, asymetrical 0+1 combinations can be interesting... so for example a system I used to admin at work had a raid 0 array that was 8x 2G, and it had a single 20G drive. The 2G drives were screaming fast, the 20G drive was no where near. It was setup with a raid 0 across the 8x 2G drives, yeilding 16G of very very fast storage, which was then raid 1'd with a partition on the slow 20G drive. (I wish I knew how, but somehow one of my co-workers convinced a bsd kernel to do the raid 0 async, so it didn't slow us down.) On more than one occasion, one of the fast 2G drives would hoark and take out that entire array... users wouldn't even notice, other than "things got slow" and as soon as we could replace the drive and resync the mirror then things were back to normal.
Personally, all of my mass storage is on the network... gigabit ethernet attached to my workstations. On there I have 2 raid arrays, one is "the vault" it's 4 drives wide, 200G per, in raid 5. The other is "scratch space" which is 6 drives wide (4 of those are partitions on the same 4 drives as above), 100G per, in raid 0. so if I loose any one drive, the scrach array is gone. But I'd have to loose 2 of the 4 300G drives to loose my vault. The whole pile is in a box with an amd64 mobile cpu, and all the fans are thermally sensitive... system is quieter than my mac when not in use... and about equal to it if I start really hammering on it. Of course, I'm a systems engineer... so for me, this was a fun side project. Normal people wouldn't likely have this kind of setup at home... or so my wife tells me.
http://wall-art.smugmug.com/
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second, i use a gigE networked solution as well....except that i don't have the death star as my network storage. I just have a couple old HD's on an old p3 in my basement. I use 1 drive for live storage, then back that up nightly to the other slower one. What kind of transfer speeds are you seeing across the wire? My whole exposure to HD performance and RAID was from troubleshooting why i was only getting 30MB/sec.
/not a network engineer, but i pretend to be one when my wife is around
I am starting to think myself that a backup service might be better than my own backup solution. It may actually cost less and I don't have to manage it and it's off-site.
Have you or anyone you know had any experience with photoshelter.com? Do they provide an automatic backup tool or do you have to upload images to them?
Is there a reason you don't use smugmug as your online backup? Do you shoot RAW?
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If that's all you have there... sure... smugmug makes for a nice off site backup. Personally, I use those arrays for a LOT more than pictures... I've got source code out there in the vault, and build trees on scratch... and financial data that i'd rather not loose, and don't want to put on the net. As with anything, there are engineering tradeoffs... if all you need is a place to keep your archives of photos safe, then yeah maybe some place online ain't a bad idea.
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NFS is the simplest and slowest (there are no stinking windows machines on this lan, if there were, samba would provide the equivalent support.) Without doing any tuning I get about 20 MB/sec (bytes, not bits). With a well tuned environment, you can get that up to max(raid array, network). In my case, I know the raid array is capable of delivering ~55 MB/sec, so that's the target for a tuned nfs implementation. At the moment I've not bothered to fully tune the environment, because I have two 100Mbit machines (the wife's mac mini for example) and the tuning options I'd like to use would adversely affect it.
If you have a purely gig network, some things to consider playing with: jumbo frames, network buffer windows, nfs mount options. The first thing I always do for tuning is to bump the read and write sizes up to 8k, even on a non-optimized network, that can have an impact on large data throughput. The second is to be sure your network stack has it's send/recieve windows large enough that it can keep the wire full... that can also have a huge impact, but it can have adverse side effects for connections other than your nfs mounts, so some testing and adjustment maybe needed on that.
Raw network pipes is another option I use alot... it *will* saturate the network at 128 MB/sec. (that's "gigabit ethernet"'s rated capacity.) This is usefull primarily when you have a significant amount of data on one machine that you want to move to another machine in a hurry. You really need to be on a unix box to use these... though I think there maybe a way to do it on windows. Look at the "netcat" or "nc" command's man page for details on what it does. In my case the "normal" use is two command prompts on my desktop running:
and Like I said, this *can* saturate the network, and I have done so to the annoyance of my wife a time or two. Also depending on the data you have, the gzip compression option to tar might hurt you more than it helps. This is the process I use to move photos from my camera to the vault after I do raw conversion and thumbnail generation here on my workstation.
This setup on one of my older machines never managed to fully utilize the network... some digging revealed the nic in that machine wasn't capable of handling that much data... replaced it with a better card (that was 1/4 the price!) and it now is able to hit 60MB/sec easily, which I fear is the limit of someother piece of it's architecture. Another thing that method sent me searching on was switches... I now have a netgear gige switch in the house, which can keep up with a lot of data going through... I used to have a switch from some no name company that would be fine for about 2 minutes of use... then start dropping packets, which put the transfer into the retransmit penalty box.
Another method I use to speed up the work, is to work locally on the storage box when I can. So forexample when I'm doing organization or cleanup of data, I shell in... when I'm prepping iso images for backups, I shell in. The theory is that the control connection as it were is lighter than the data connection.
http://wall-art.smugmug.com/
What mobo has RAID 5? Wouldn't you have to do this as a software solution? I wouldn't care for that. I've yet to find a decent cost solution for a hot swappable RAID 5 hardware appliance. What are you using for your "vault", and at what cost?
Yes, software raid5. Doing the math in software on the cpu, versus in software on an external card really doesn't matter much. The only place you're going to find real high end *hardware* raid5 is on top of the line scsi cards.
The case was recycled from an old machine, ditto power supply, and fans, also 2 100G ATA 133 drives. The load source for the system, and root filesystem is an old usb flash key.
The mobo is an AOpen AK86-L, $67
The CPU is a Mobile AMD64 3000+, $120 (I chose mobile because of cool'n'quiet)
A stick of cheap, but name brand, DDR400 memory, 256M for $20
2 cheap dual channel ATA133 cards plus 4 36" ATA133 cables, $36
4 maxtor 300G ATA 133 drives, $750
So the hardware total was roughly: $993, plus some gear that was sitting around.
The 4 300G discs are partitioned into a 100G slice and a 200G slice.
The 4 200G slices are in a raid 5 as vault.
The 4 100G slices, plus the two 100G drives, are in a raid 0 as scratch.
I know of *no* hardware raid solution that would allow the above setup, and that was originally done out of necessity... you see those two 100G drives were my old "vault" array, so there was 98G of data on there that I didn't want to loose.
http://wall-art.smugmug.com/