LaCie Little Big Disk versus
Promise Pegasus R4
Posted Friday, November 11th, 2011, by rob-ART morgan, mad scientist
Updated November 19th, 2011, with Finder Duplicate and OS X Restart test results.
We wanted to know if two striped drives in the LaCie Little Big Disk (LBD) Thunderbolt would transfer data as fast as the same two drives in the Promise Pegasus R4. To stress both enclosures to the limit, we used dual 6Gb/s solid state drives (SSDs). Then for perspective, we included two models of notebook hard disk drives (HDDs).
AJA System Test was used to measure how fast you can capture and playback HD video. Settings were 4.0GB File Size, 2048x1556 10-bit RGB Video Frame Size, 335 frames, file system cache disabled. (RED bar indicates the fastest)
PR4 6Gssd = Promise Pegasus R4 Thunderbolt RAID enclosure (two 120G OCZ Vertex3 Max IOPS 6Gb/s SSDs in RAID 0 mode)
LBD 6Gssd = LaCie Little Big Disk Thunderbolt enclosure (two 120G OCZ Vertex3 Max IOPS 6Gb/s SSDs in RAID 0 mode)
PR4 Hybrid = Promise Pegasus R4 Thunderbolt RAID enclosure (two 500G Seagate Momentus XT Solid State Hybrid HDDs in RAID 0 mode)
LBD Hybrid = LaCie Little Big Disk Thunderbolt enclosure (two 500G Seagate Momentus XT Solid State Hybrid HDDs in RAID 0 mode)
PR4 NoteHD = Promise Pegasus R4 Thunderbolt RAID enclosure (two 500G Hitachi Travelstar HDDs in RAID 0 mode)
LBD NoteHD = LaCie Little Big Disk Thunderbolt enclosure (two 500G Hitachi Travelstar HDDs in RAID 0 mode)
Test "mule" was a 2011 iMac 3.4GHz Core i7 running OS X Lion 10.7.2.
QuickBench's Standard Test was used to measure small random file transfer performance. The graphs show the average of 5 cycles of random transfers ranging in size from 4K to 1024K. (RED bar indicates the fastest)
FINDER DUPLICATE TEST
Real World test number one asks, "How quickly can Finder duplicate a single 1GB document on each volume?" This is intense because the volume has to read from and write to itself simultaneously. Instead of time in seconds, we calculated the megabytes per second. RED bar indicates the fastest.
"How quickly can Finder duplicate a 6.5GB folder with 145 items?"
Real World test number two asks, "How long does it take to Restart OS X Lion from each volume?" We timed three runs and averaged them. Time is in seconds (shortest bar is fastest in this case.)
1. According to AJA System Test, the Promise Pegasus R4 writes large sequential data files (captures video) significantly faster than the LaCie Little Big Disk when both are using SSDs. This is significant in that, according to the data rate calculators, 2048x1556 10-bit RGB 29.97 fps video requires 382MB/s to avoid dropped frames. The LBD falls short of this target. The Pegasus exceeds that target with either dual 6G SSDs or quad HDDs.
2. The Promise Pegasus R4 with dual 6G SSDs does random transfers faster than the LaCie Little Big Disk with dual 6G SSDs.
3. In our "real world" Finder Duplicate test, the Pegasus once again showed its dominance over the Little Big Disk. However, in the OS X Lion Restart test, the Little Big Disk beat the Pegasus three out of three. That's a head scratcher.
4. SSDs typically leave HDDs in their dust in all operations. But for some reason, when we used the Promise Utility to configure the HDD RAID 0 sets in the Pegasus, the small random speed was ten times faster than when configured with Apple's Disk Utility. This may or not translate to real world performance gains. If it does, then the Pegasus scores another victory over the Little Big Disk -- which can't use the Promise RAID Utility.
5. One thing not shown in the graphs is the speed with which SSDs process transactions -- more than 35 times more per second than an HDD.
Though we installed SSDs in the LaCie Little Big Disk Thunderbolt, you can't buy it with SSDs pre-installed -- yet.
The Little Big Disk has a smaller footprint than the Pegasus but both require AC power. The Pegasus is compact for an enclosure that accepts 3.5" drive form factor. We used Icy Docks to adapt the 2.5" SSDs to the Pegasus drive trays.
Both the Pegasus and the Little Big Disk offer a big jump in speed over the FireWire 800 and USB 2.0 enclosures used by iMac, MacBook Pro, and MacBook Air owners in the past. However, you pay a price for the speed. The lowest priced Little Big Disk is $399 (two 500G notebook HDDs). Replacing the HDDs with two 120G SSDs doubles the price. The lowest priced Pegasus is $999 (four 1TB desktop HDDs). Replace those HDDs with SSDs and the price will double or triple, depending on the capacity of the SSDs.
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