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Striping 4 Drives In Two OWC Mercury Elite Pro Duals
Related: diglloydTools, DiskTester, Other World Computing, OWC Mercury Elite Pro, RAID, RAID-0, storage, Thunderbolt, USB
See the overview of the OWC Mercury Elite Pro Dual.
With two OWC Mercury Elite Pro Dual units on hand (briefly), a thought arose: daisy chained and using one Thunderbolt port, what kinds of speed could be attained?
These two units were mismatched but were what was on hand; one had dual 4TB drives and the other had dual 3TB drives. Faster results might be expected from matched and/or faster hard drives, not that these results are at all slow!
For reliability with lower but still excellent performance, RAID 1 + 0 is advised: set each unit to mirror mode, then stripe that pair. That way, one drive in each unit can fail without loss of data or functionality.
Each unit set to Independent mode, and a software RAID-0 stripe was created from those four drives. A 2TB partition was tested. Results were similar when using hardware striping on each unit, then striping both units, but slightly faster on writes (554MB/sec vs 539MB/sec).
Performance
Testing performed with the DiskTester fill-volume command. DiskTester is part of diglloydTools. The command line version was used here.
llcR:~ lloyd$ disktester run-sequential -i 20 sr5stripe
DiskTester 2.2 64-bit, diglloydTools 2.2.0, 2012-12-15 18:05
OS X 10.9.1, 8 CPU cores, 16384MB memory
Allocating maximum size contiguous file on "sr5stripe" (2TB)...1.99TB (99.5% of volume size)
Using test size of 4GB, 4MB at a time at start (0%), within a 1.99TB test file.
.... elided ....
Monday, December 30, 2013 at 20:08:16 Pacific Standard Time, volume "sr5stripe" (2TB)
------------- Averages for "sr5stripe" (4GB/4MB, 20 iterations) ------------
Iteration Write MB/sec Read MB/sec
1 544 651
2 524 645
3 540 651
4 541 641
5 541 651
6 542 651
7 537 651
8 541 651
9 539 652
10 542 651
11 539 651
12 541 651
13 541 638
14 540 651
15 540 640
16 540 652
17 536 640
18 541 651
19 541 650
20 532 651
Slowest 524 638
Fastest 544 652
Average 539 648
Median 541 651
Range 20.6 13.8
Command "run-sequential" executed in 279.84 seconds on Monday, December 30, 2013 at 20:12:56 Pacific Standard Time


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