Speeding up Photoshop with an External Drive

By Ctein

You're about to read a follow-up to an article that's yet to be published. I'll have an article in the July/August PHOTO Techniques magazine on how to extract the maximum performance from Photoshop. Post-deadline, Other World Computing loaned me a couple of high-performance external drives to test as Photoshop scratch drives. I report on them here. Isn't time-twisting fun?

The OWC Mercury Elite-AL Pro 'Quad Interface' drive (above) contains a 750 GB, 7200 RPM, 32 MB cache drive and has eSATA, FireWire 800 and 400, and USB2 ports. It lists for $230. I connected that drive to my MacBook Pro with the $39 APIOTEK EXTREME Dual eSATAII Express Card 34 Adapter (right).

The OWC Mercury On-The-Go FireWire 800/400 + USB case with a Hitachi 200 GB, 7200 RPM, 16 MB cache drive runs $190 after rebate. That's not the biggest but it is the fastest laptop drive out there. I installed one in my MacBook Pro and it has a sustained throughput around 60 MB per second, says Lloyd Chambers' DiskTester. That's twice as fast as many laptop drives.

My test was a merge of twenty 35 MB images into a single panorama, which you can kinda see above; the original is almost 60 times bigger! You can view a small section at 100% scale below. Photoshop reserved 26 GB of scratch space to render the assemblage. Using my laptop's internal drive as the scratch drive, Photoshop took around 10 minutes to assemble the panorama.

Next I tested the On-The-Go drive. Connected as a FireWire 800 device, DiskTester reports it's as fast as my internal drive; connected via FireWire 400, performance dropped by over 40%. How did this translate into Photoshop scratch performance? Via FireWire 400, rendering time was identical to the internal drive, while FireWire 800 trimmed a full minute off of the render time. The results would more dramatically favor the On-The-Go drive if I were running a "stock" internal drive or a normal assortment of foreground and background tasks (I can't test that because it's just about impossible to get reproducible results).

Just for a joke, I tried USB2, which slowed the drive by a factor of 3–4! Maybe with the right drive and the right glue circuitry USB2 lives up to its specs, but it never has on any hardware I've used. Worse, Photoshop doesn't play at all well with USB2; it still hadn't finished rendering the file after over 2 hours! You want good scratch drive performance? Stick with FireWire or eSATA.

The OWC Mercury Elite-AL Pro sustained eSATA read speeds approaching 95 MB/s. Write speeds averaged 80 MB/s, but there was a great deal of variation in write speeds that I could not pin down; sometimes it was low as 70 MB/s, other times it matched the read speeds. No question it's fast; I'm just not sure exactly how fast.

The On-the-Go Drive

Under FireWire 800 performance dropped by a modest 15%. FireWire 400 racked up 38–40 MB/s, close to the theoretical limits. A drive this good needs FireWire 800 or eSATA. Still, even FireWire 400 scratch performance was respectable, trimming almost a minute off the rendering time. FireWire 800 clipped almost 2 minutes and eSATA saved almost 3. That's really impressive.

Both drives are good ways to goose up Photoshop. If you are a traveling photographer, the On-The-Go drive will perform at least as well as your internal drive and probably substantially better. If you're working from a desk, the Mercury Elite drive will give Photoshop a real kick in the pants.

Two tips—first, don't make the mistake of filling these drives up with other files if you want to use them for scratch. Typically there's a factor of two performance difference between the front and back ends of a drive. You want that fast front space for Photoshop scratch files. Reformat the drive as two partitions, reserving the "front" end of the drive for a dedicated scratch partition.

Second, if you really want maximum performance, set up a RAID 0 SATA array, like Lloyd recommends on his website. I expect that doing that would cut my photomerge rendering times by a full factor of two over the internal drive. For a several hundred dollar investment, that's a pretty good performance return.

_____________________

Ctein

Comments

[Charlie]

Great stuff Ctein,

I don't understand all of what I read here but was actually wondering about this. I have an OWC Elite Pro as a back- up drive to my G4 Powerbook. The drive in the notebook was replaced and is pretty quick but I would not complain about a boost in speed.

My only issue would be the noise factor on my OWC. Since it's a back up it is rarely on but it is a touch loud and a bit of vibration is present. Otherwise my set up is dead quiet.

Yet another great reason to read this site everyday. We actually own both those drives.....I shall look into it.

Thanks

[Guillermo]

For this kind of work (the panorama thing) you could use a faster internal drive just for process work, and then save it elsewhere. Its a useful way for some short video edits too.

[Ken Lee]

Great article, and very helpful.

One small grammatical suggestion: To say that with FireWire 800, performance dropped by over 40%, suggests that there was a decrease or loss of performance. Apparently, there was an improvement in performance.

[Cyril]

Excellent technical article.

Just a naïve question: if you format a disk as two partition, can you be sure that the first partition is the "front-end"? Or do you need to check that somehow after partitioning?

[erlik]

Not counting the rebate, the 200 GB box is whopping $10 cheaper. Even with the rebate, for $40 you get 550 GB, 16MB buffer more and an eSata connection in bargain, too.

Okay, so the second option is a 2.5" disk and has a 6" shorter box. Still, looks like no competition to me.

Nice review. Thanks!

[Robin P]

(Only a little bit sarcastic)
Very strange - I wouldn't want to do more than a simple crop/resize of an image on any laptop, never mind anything as complex as render a panorama!
Surely this sort of work is better done on the real computer (with fast internal drives) when you get home?

Cheers, Robin

[toto]

I went back and read the article over again. From what I understand, "connected via FireWire 400, performance dropped by over 40%" refers to a drop in performance of FW 400 compared to FW 800. "Under FireWire 800 performance dropped by a modest 15%" refers to a performace drop of FW 800 compared to eSATA.

[Ctein]

Dear Ken,

Here's the sentence you're referring to:

"Connected as a FireWire 800 device, DiskTester reports it's as fast as my internal drive; connected via FireWire 400, performance dropped by over 40%."

It's correct as written-- FW 800 is faster than FW 400. In this case, the driver is capable of higher data rates than FW 400 can support, so there's a substantial performance drop going down from FW 800 to 400.

pax / Ctein

[Ctein]

Dear Charlie,

I've got enough other devices running fans in my office that I can't speak to the noise of the drive. I can't hear it above the fan in my MacBook Pro, but then there's also a desktop machine in here with several fans running, et cetera. If noise is a really big issue for somebody, that would be an argument for the On-The-Go drive is, as they are small and quiet.

Dear Guillermo,

That's rarely a bad idea, but it may not make a performance improvement. It really depends on how fast your machine is and how fast your drives are. I tested saving the finished file to the internal drive, the FireWire 800-connected On-The-Go drive, and the eSATA-connected Mercury drive. Save times, in order were 5:33 minutes, 5:43, and 5:03. It did not appear the drive contention was an issue, it looks like it's purely dependent upon the speed of the drive. There was no difference in run times putting the source files on different drives; all the drives on my system ran faster than Photoshop could read and interpret the files.

Dear Cyril,

The first partition should be the front end.

Dear Erlik,

These are different solutions to different problems. If you're tied to a desk, you don't need the 3.5" x 5.5" x 1", bus-powered, 11 ounce On-The-Go drive. If you're traveling, you don't want to haul around the 5.5" x 9" x 1.4", AC powered, 3 lb Mercury Drive. That was why I tested both of them; they address very different needs.

~ pax \ Ctein
[ please excuse any word salad. MacSpeech in training! ]
======================================
-- Ctein's online Gallery http://ctein.com
-- Digital restorations http://photo-repair.com
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[Ctein]

Dear Robin,

You're behind the times if you think laptops aren't appropriate to serious work. Performance wise, a high-end laptop like mine ranks in the high tier. Go check out the various published cross-platform benchmarks if you don't believe me. The laptops have two disadvantages over desktops -- the screen quality and expandability. Nothing I can do about the screen quality in the field; at home I tie the machine to a nice 23 inch Cinema Display.

Expandability-- I did wrestle over getting a new laptop or a new desktop first, primarily because I could put 8 GB of RAM in the desktop machine and only 4 in this laptop. But 4 GB of RAM was sufficient to let me assign a full complement to Photoshop; where I lose out is not having the 4-8 GB range to use as a virtual scratch drive. The other big compromise is in hard drive size. My internal hard drive, cranking a reliable 60 MB per second, is considered a pretty respectable drive by today's standards on any machine. Send me benchmark results for your desktop machine and I'll be glad to match them against what I've got here. The laptop limitation is that I can't get that kind of performance in a drive bigger than 200 GB.

But I'll tell you something, because of the limitations on screen quality the kind of work I am likely to do on a trip would include assembling the panoramas there, if that were my druthers, because that's work that isn't compromised by lousy screen quality. What I can't do in the field off a laptop is refinements of tone and color. But performance? Really, not an issue!

The notion that people can't and aren't doing serious photographic and Photoshop work on a laptop is simply wrong. It may very well not be anything you would choose to do, in which case to borrow a phrase from the performing arts, "you are not the audience" for this column.

~ pax \ Ctein
[ please excuse any word salad. MacSpeech in training! ]
======================================
-- Ctein's online Gallery http://ctein.com
-- Digital restorations http://photo-repair.com
======================================

[Matt]

Quote: "My test ... which you can kinda see above; the original is almost 60 times bigger!" Should that be 60 wide x 60 high (3600 times bigger)?

[Stephen Best]

"My internal hard drive, cranking a reliable 60 MB per second, is considered a pretty respectable drive by today's standards on any machine. Send me benchmark results for your desktop machine and I'll be glad to match them against what I've got here."

Not meaning to boast but my Mac Pro with scratch striped across three cheap SATA drives delivers over 250MB/sec. The main limitation of notebooks, as you point out, is maximum RAM capacity (and to a lesser extent memory bandwidth). There's a huge performance difference between 4GB and 8GB+ for the file sizes I typically work on. The fastest I/O is the one you never do.

If you're serious about Photoshop performance, a desktop (or rather floor stander) is the way to go. The current models are actually pretty quiet, even loaded to the gills with RAM and a full complement of drives. Check them out.

[Robin P]

""you are not the audience" for this column."
Well, maybe, as I'm not a professional photographer.
I'm just concerned by the number of people falling for the hype over "desktop replacement" laptops which have poor expandability and very poor value for money compared to the traditional desktop PC.
Glad we agree over the poor screen quality.

"Send me benchmark results for your desktop machine"
As DiskTester is only for Macs I can't run it but HD Tune tells me that my 160GB system disc does 60MB/s and the 500GB disc I use for scratch & storage partitions does 80MB/s. I gave up on RAID a couple of years ago as required HDD size seemed to double every 12 months and I like to keep the machine cool & quiet with just two drives.

Cheers, Robin

[Ctein]

Dear Matt,

Yeah, since I was referring to the visual representations, it's linear dimension, not file size.

Dear Stephen,

Agreed, as I mentioned at the end of the article, a SATA RAID array is the way to get maximum performance. Nice thing is it doesn't much matter if it's an internal or external array.

Can't afford to buy more than one machine at a time. New laptop had higher priority than new desktop. Truth is, I'm not *that* serious about Photoshop performance that it overrides all other considerations.

pax / Ctein

[Ctein]

Dear Robin,

You might want to give RAID another look. The landscape's changed a lot in the past few years, what with cheap SATA3 cards and drives. I don't think much of RAID for general use, but for scratch purposes 2-4 of the smallest drives you can buy will give you incredible throughput and more scratch space than you'll ever need.

If you don't find Photoshop using the scratch disk much then it's of no import, but if it's eating into your time this is probably the most cost-effective way to improve your system's performance.

pax / Ctein

[Ivan P.]

Thanks for sharing this information Ctein.

I have a 120 GB external firewire 400 drive which I use for backup. If I repartition it, how much should I set aside for the scratch disk?

[Stephen Best]

"I don't think much of RAID for general use, but for scratch purposes 2-4 of the smallest drives you can buy will give you incredible throughput and more scratch space than you'll ever need."

Actually, larger drives have better throughput due to higher density. The scratch can just be a thin stripe at the outer rim (un-journaled). The rest of the drive space can be used for file storage (and mirrored if required). As long as there's little contention, this arrangement works great and is dead easy to set up with a modern OS.

[Ctein]

Dear Ivan,

Well, for the rather monumental task I gave Photoshop in this article, it reserved about 25 GB of scratch space. I've never done anything else that came close to needing that much space.

Remember that you can assign more than one scratch drive, in case you guess short. There are also good utilities out there that can repartition a live drive, should you wish to expand or contract the scratch space later if you guess wildly wrong.

pax / Ctein

[Ctein]

Dear Stephen,

True; it's one reason I chose the 750GB OWC drive to test.

It's a bit of an optimization problem. Two more expensive, big drives vs four small, cheap drives, for example. At some point it becomes overkill; I don't know what the drive is in the Mercury case, but four of those would exceed the bandwidth of SATA3. There should also be a point of diminishing return where the drives will be running only as fast as Photoshop can stoke them. What that point is will depend upon one's system.

There's a bunch of stuff I don't know about just how Photoshop utilizes the scratch drive, so take all of this as tentative.

pax / Ctein

[Ken Lee]

You are right. I read it backwards. Oops !

Thanks for the article !