November 10, 2012
Photoshop CS6 File Save And Open Performance

I've been getting tired of waiting for Photoshop CS6 (v13.0.1) to save my PSD file when I'm done processing an image. That minute or so wait seems like forever. Now, since I'm a gear head, I store my files in a RAID(0) enclosure that's connected to my MacBook Pro (mid 2010, 17-inch, 2.8 GHz Intel Core i7) via an eSATA connection to get a decent file-access speed. Because that storage system didn't seem to be sufficient, I started to consider getting a small external SSD (Solid State Drive) where I could store a set of images while I was working on them and then I'd move the processed images over to the significantly larger RAID(0) enclosure for long-term storage. Well, before shelling out some bucks, I decided to test the file I/O using the drives that I already have.

• HD: Hard Drive, one internal 2.5" 500GB Hitachi 7200 rpm drive
• HD RAID(0): Hard Drives in RAID(0), two 3.5" 1TB Hitachi 7200 rpm drives in an OWC Mercury Elite Pro RAID enclosure connected by eSATA
• SSD: Solid State Device, one internal 240GB OWC Mercury Electra 3G

Based on pure data throughput, the HD RAID(0) can transfer data about twice as fast as the HD, and the SSD can transfer data about three times as fast as the HD. The chart above shows the time to save a 21MP file comprised of four (4) layers of image data and my regular adjustment layers including a Silver eFex Pro layer. By default, Photoshop saves compressed files (the blue bars), and I was shocked when I actually timed how long it took to save the file to the various drive systems because there was hardly any difference. I did some Googling and that's when I discovered that Photoshop saves compressed files by default and the compression is usually a significant part of the save operation. So, I turned off compression (Preferences > File Handling, then check Disable Compression of PSD and PSB Files), and that significantly reduced the time required to save the files (the red bars). If I process 50 images, something I can do if I process all day, I can save 50 minutes by saving uncompressed files! The file size went from 587.9 MB (compressed) to 1.66 GB (uncompressed) — 2.8 times bigger. While I'm not excited about the significantly larger file size, I'm really excited about the reduced time required to save the file. Plus, it doesn't matter too much how fast the storage system is, so I won't have to invest in a new SSD-based temporary storage drive. (I was planning to get a 6G SSD which is about four or five times faster than the HD.) To reduce files size, it's possible to run a Photoshop action in batch mode to save the files in compressed format, and that's something that can be run while I'm doing something else. I also tested the time required to read the compressed and uncompressed files from the various storage devices. Yes, it actually takes longer to read the compressed files because part of that time is spent uncompressing the data.

So I won't be getting a new 6G SSD to hold the image files I'm working on and I'll stick with the HD RAID(0) system instead of switching to a single-drive external enclosure that I briefly considered after seeing the timing results. The single-drive external enclosure would use less electricity which is a plus when operating off of solar power, but it's about twice as slow to open the starting TIFF file in Photoshop and I don't like waiting for my computer to do something trivial. Oh well, no new computer gear for me right now. :)