It's been two years since the last major change to my photo storage setup. The same considerations apply now: cost, performance, and simplicity. Once I decided to move away from an all-encompasing Mac Pro to an iMac, I needed to find a way to bring my photo storage setup along with me.
Honestly, the options for external storage I had this time were very similar to those of two years ago. Drobo's continue to be poor options due to low performance and questionable reliability. Direct attached hardware RAID enclosures are still extremely expensive and probably not worth dealing with for my needs.
That really just left NAS enclosures versus Thunderbolt enclosures. In terms of price, the two options are virtually the same. Good 4-bay NAS and Thunderbolt enclosures tend to run anywhere from $400 to $700 without drives. Fortunately the hard drive manufacturers seem to have recovered from the typhoons that wrecked havoc on their production pipelines and hard drive prices have come down quite a bit. 4TB drives are well under $200 now, and 6TB drives are in the sub $300 range as well.
I decided to go with a Thunderbolt enclosure purely for performance reasons. Large capacity disk drives in a RAID configuration blow past what iSCSI interfaces can offer pretty quickly. 300MB/s read/write isn't uncommon at all, with RAID 5 enclosures quickly surpassing 500MB/s. That's faster than many entry level SSDs, all with hard disk drives. Another reason was backup. You can easily backup a Thunderbolt enclosure to services like Backblaze, while backing up a NAS to an online backup service is incredibly difficult to do. This way I get to maintain my backup setup with Backblaze, which was a big deal for me.
Hardware
I didn't have to shop long to find a Thunderbolt enclosure that would suit my needs. The OWC Thunderbay 4 is an excellent option with terrific performance and a very reasonable price. The Thunderbay 4 is purely a JBOD enclosure that you can configure any way you want using software RAID. While some forms of proprietary RAID, including the popular SoftRAID 5 are supported, I decided to go with Disk Utility and RAID 1+0 for my setup. I'm sure some people have had great success with SoftRAID, but things like questionable Yosemite support and possible issues around future upgrades were enough to convince me not to try it. I've used Disk Utility RAID for nearly 10 years without issues, so I decided to keep trusting it.
My experience with the Thunderbay 4 so far is mostly positive. The performance on the enclosure with RAID 1+0 is excellent. Here's a screenshot:
The enclosure is mostly quiet while in normal operation. The fan is just barely louder than the 2010 Mac Pro's case fan. It's far quieter though than the iMac's fan on full blast. Anything above 1600 rpm on the iMac's fan will drown it out.
I can, however, hear hard drive noise over the fan from time to time. This tends to be most prevalent when the drives are spinning up or spinning down. I haven't decided what to do about this yet. I'm wondering if placing the enclosure on a rubber mat would insulate some of the noise. I'm also wondering if it's a sign that the hard drives I ordered aren't perfect. It isn't annoying enough for me to abandon the setup or change directions (I've certainly used louder hard drives than these before), but, it's not quite what I was hoping for.
In addition to the Thunderbay 4 I also picked up an OWC Helios 2 PCIe Expansion Chassis to house two PCIe SSDs that I got last year to help extend the life of my 2010 Mac Pro a bit. I already knew this chassis existed when I got the SSDs, so I knew that I could carry them with me if I ended up getting a new computer later.
Fortunately, that has worked out extremely well! The Helios 2 is an incredible product. Transferring the SSDs to the Helios was completely painless. It booted up and recognized the drives immediately, and even preserved their RAID-0 volume configuration. Just awesome.
The performance of the drives via Thunderbolt 2 is also amazing. Here's a screenshot:
System Configuration
Getting all of the necessary hardware is only the first step in the process. How it's all setup to work together is just as important to maximize both performance and usability of the overall system.
I broke everything out into three main volumes:
iMac SSD - The internal SSD on the iMac which is used only for the operating system, applications, and other things like Dropbox and software repositories that can be easily recreated or downloaded from the cloud.
Photo SSD - The striped SSDs in the Helios array combine to create an incredibly fast volume for photo library storage. The only thing on here right now is my Aperture library, which includes metadata, thumbnails, and previews of all the images. Soon this may also include a Photos library or a Lightroom library, but for now it's just Aperture.
Photo RAID - The 4 drives in the Thunderbay enclosure combine to create a 12TB fast and redundant bulk storage volume. This is where the bulk of my data lives, including over 260,000 RAW photos and a few video projects. This drive also contains mirrors of the other two SSDs for backup purposes.
With this system I wanted to maximize performance, redundancy, and portability.
Performance is self explanatory. Redundancy is hugely important to me. Not only do I have a full backup running automatically to Backblaze, and a periodic offsite backup in a secure location, but I want to have as close to full redundancy onsite as I can as well. Part of that strategy is using something like RAID 1+0 to gain 1-2 disk fault tolerance on my primary storage, but it's also got to include backups of my boot volume and photo library. That is achieved by cloning the two SSD volumes back to the bulk storage array.
The third criteria, portability, is an interesting one. What I realized while researching this is that having most of my storage needs met using Thunderbolt that I gain an unprecedented level of portability of my storage system. If I were to decide to use a laptop instead of a desktop, or move to a Mac Pro instead of an iMac in a few years time, all I would have to do is plug in two drives and I'm ready to go. No longer being tethered to internal storage is something of a relief to me now that I think about it this way.
Conclusion
When I wrote about my solution to this two years ago I knew I was essentially choosing the stop gap solution.
“Hopefully this system will buy me another 2-3 years of storage. The bet I am essentially making is that there will be a better solution to this problem in 2-3 years. That will likely be near the end of life for my MacPro, and if Apple is moving away from towers then perhaps Thunderbolt mass storage will be cost effective by that time. Or maybe there will be 8TB HDDs then, and I’ll just upgrade to two of those :)”
I had 2TB of photos, and I knew I was adding over 600GB a year, so I hoped that by the time I ran out a better solution would be available. Thankfully, I think it now does, in the form of cost effective Thunderbolt mass storage.
I actually could have applied the same logic again, and simply swapped out my 4TB drives with 6TB ones and used my Mac Pro as a giant aluminum NAS machine. But in reality, that would have just been prolonging the inevitable. Moving to external storage was necessary and gives me a lot more freedom and flexibility with my data. It also gives me some degree of longevity for this setup. At my current rate of photo taking with a Canon 6D I am adding around 750GB of RAW photos per year. This time around, I'm going to hope that this system buys me another 5-6 years of storage.
I want to also thank macperformanceguide.com again for all of the wonderful work on Mac performance and storage. I found their resources to be incredibly beneficial.