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HGST Ultrastar He8 Performance: Speed vs Capacity Utilization
This page assesses sustained transfer speed performance using five brand-new samples.
Hard drive speed varies by capacity utilization
Read more: Drive Speed of 6TB vs 8TB Hard Drives.
As data fills out a hard drive, it first occupies the outer and faster tracks (at least on OS X). Thus data rate (MB/sec) is a direct consequence of C=πD for track circumference. See the multiple articles in the Drive Capacity and Speed articles, in particular 4/5/6TB Hard Drives: Higher Capacity Boosts Real-World Performance.
At much lower cost than Apple, with more options.
Lloyd recommends 64GB for iMac or Mac Pro for photography/videography.
Speed vs capacity utilization, 5 samples
DiskTester fill-volume used on freshly-erased drives with Spotlight and Time Machine disabled. Throughput figures are real-world figures through the OS X file system.
Sustained transfer rate is graphed using the output from DiskTester fill-volume, which provides 1000 data points across the entire capacity of the drive which can be pasted into the supplied spreadsheet graphing template.
Overlaid on the graph are the results from five (5) samples of the HGST Ultrastar He8 hard drive. The five samples of the HGST Ultrastar He8 show a tight performance band alone and as a group. It is an impressive performance; most consumer drives show far more variation. This tight performance spread is ideal for RAID. The average speeds vary by less than 2% among the five drives:
Average MB/sec across capacity Write Read Sample 1: 160 163 Sample 2: 160 162 Sample 3: 160 162 Sample 4: 163 165 Sample 5: 160 162
Also evident as discussed in various Drive Capacity and Speed articles, speed drops across the capacity, with a loss of about 47% from empty to full (about 195 MB/sec down to about 102 MB/sec). Video capture users take note! This behavior is common to all hard drives by C = πD (data rate at fixed data density is proportional to track circumference).
Because of the speed drop-off (as with all hard drives), one strategy for getting the best possible hard drive speed is to use higher-capacity hard drives not for capacity, but for higher performance for the same amount of capacity utilization. See Why You Need More Space Than You Need and 4/5/6TB Hard Drives: Higher Capacity Boosts Real-World Performance. Another tactic is to partition the drive into two or more volumes, utilizing the faster volume performance as needed, e.g. slicing off the first 4TB of an 8TB hard drive and either not using the remainder, or making another volume to be used for less performance sensitive purposes. If this were done, the fast 4TB would range from ~195 MB/sec to ~165 MB/sec (500 mark on the X-axis).
All that said, the performance dropoff of the HGST 8TB Ultrastar He8 over its capacity is more severe than usual (nearly 50%)—disappointing for a high-end offering. Not until the ~3TB mark can the He8 match the sustained transfer performance of its 6TB NAS sibling. So unless one is actually storing 5+ TB of data, the HGST 6TB Deskstar NAS looks to be a better choice for overall performance (setting aside usages like RAID).
In 2009 Mac Pro internal bay
Some video users still favor the 2009/2010 Mac Pro tower, which has four internal bays (and two more with appropriate brackets), making it possible to have up to six internal drives. With 8TB drives, that means 48TB is possible in the 2009/2010 Mac Pro, all internal. Or 32TB using only the four standard bays.
The HGST 8TB Ultrastar He8 work great in the 2009 Mac Pro, including seeing no sleep/wake issues. Performance is solid, as can be seen in the graph below. It is within 5-10MB/sec of the tests on the 2013 MacPro, above.
There is one minor catch: the drive bolt holes are changed in some newer-model drives like the He8. To mount the drives in the internal bays, use the nifty OWC Hard Drive Bracket
for 2009-2012 Mac Pro. The bracket is compatible with both newer and older drive mounting holes (simply use the screws in the matching holes for the drive).