Here at CMP, we recently started dipping our toes in the Thunderbolt water, specifically with a previous-generation iMac. I picked that model because, while not slim like the new ones, the RAM can be easily upgraded and it still had a legacy Firewire port.
For these tests, I used a LaCie eSATA hub, a NewerTech Voyager S2 drive toaster, and a 3 Gb/s Western Digital “green” SATA hard drive. I also tested Firewire 800 speeds using a 2-drive RAID, the OWC Mercury Elite AL-Pro. That 2TB drive has USB, Firewire 400 and Firewire 800 ports, but I only tested the FW800. Finally, I also tested a 120GB 6 Gb/s SanDisk Extreme SSD and the Seagate GoFlex Thunderbolt adapter.
The software used for the testing was the excellent free utility from Blackmagicdesign called Disk Speed Test.
So, now that you know the background, here are the results, some of which were a little surprising.
I benchmarked the WD drive on a different computer connected to an eSATA card at 45.2 MB/s write and 44.5 MB/s read.
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Disk | Connection notes | Write Speed in MB/s | Read Speed in MB/s |
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WD 1TB | BENCHMARK | 45.2 | 44.5 |
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WD 1TB | LaCie to toaster | 44.3 | 44.9 |
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2TB Raid | Apple TB-to-FW800 on iMac TB port | 75.9 | 54.2 |
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2TB Raid | FW800 iMac port | 66.7 | 54.9 |
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2TB Raid | LaCie TB out to Apple TB-to-FW800 | 64.7 | 54.9 |
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SSD | LaCie to toaster | 93.5 | 129.4 |
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SSD | Seagate GoFlex on iMac TB port | 151.2 | 365.4 |
Note the amazingly fast read speeds on that SSD when connected via the GoFlex adapter! This could be because the toaster I’m using might not support the 6 Gb/s connection that the SSD is capable of, but the GoFlex does. There is also likely an overhead penalty for using the LaCie hub.
Generally, the LaCie seemed to perform so close to the benchmarked speed on the bare drive in the toaster as to be functionally equivalent. This is a big deal for us, since we have toasters in every room and like the speeds of eSATA. For our MacPros, we have the option of adding eSATA cards or running cables from unused motherboard ports, but that was always a kludge on the iMac, at best.
So, what do the numbers really mean? Well, Avid codecs like DNxHD 220 are measured in megaBITS per second, not megaBYTES, so to make the numbers match you have to divide by 8 (because there are 8 bits in a byte). Ergo: DNxHD 220 requires throughput of 27.5 MBps per stream. ProRes 422 HQ is also a 220 Mbps codec, requiring 27.5 MBps per stream. Ideally, we’ll need an eSATA RAID connected via the LaCie hub in order to do any serious editing on the iMac, but this really does open up our options. Or I suppose we could just edit 13 layers straight from the SSD!

Well friends, the National Association of Broadcasters’ yearly convention is coming up, and I thought I would put a few tips on the blog. Although I missed going last year (which ended my 18-consecutive-year streak!), I’m very likely going to head out to the desert again this spring.





