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RAID 1+0: Striping a Pair of Mirrors for Fault Tolerance
Related: fault tolerance, Other World Computing, OWC Mercury Elite Pro, RAID, storage, Thunderbolt, USB
With two OWC Mercury Elite Pro Dual units on hand (briefly), a thought arose: daisy chained and using one Thunderbolt port, how about an easy-as-pie fault tolerant setup?
Some workflow environments have a “cannot be down” operating principle. Examples might include a service bureau, where jobs have to be finished on some deadline (e.g., by 5PM).
Fault tolerance means some degree of failure can be tolerated with no data loss and no loss of functionality. A RAID-1 mirror is the most basic kind of fault tolerance, but sometimes more performance is desired. Thus, a RAID-0 stripe of RAID-1 mirrors comes to mind.
With a pair of the OWC Mercury Elite Pro Dual units, it is easy to make a striped pair of mirrors (RAID 1+0), which achieves both high performance and fault tolerance for critical workflow environments:
- Configure each OWC Mercury Elite Pro Dual unit to Mirror mode.
- Make a RAID-0 stripe of the two units.
With this setup, one drive can fail in each unit with no data loss and continued functionality (replaced the failed drive ASAP).
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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!
llcR:~ lloyd$ disktester run-sequential -i 10 r1+0 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 "r1+0" (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 20:37:25 Pacific Standard Time, volume "r1+0" (2TB) --------------- Averages for "r1+0" (4GB/4MB, 10 iterations) --------------- Iteration Write MB/sec Read MB/sec 1 318 318 2 302 317 3 316 317 4 316 317 5 319 316 6 319 316 7 318 316 8 318 317 9 316 318 10 317 319 Slowest 302 316 Fastest 319 319 Average 316 317 Median 317 317 Range 17.2 3.22 Command "run-sequential" executed in 261.02 seconds on Monday, December 30, 2013 at 20:41:46 Pacific Standard Time
High capacity, high-performance fault-tolerant storage for photography and video.
Non-RAID or RAID-0/1/4/5/10.
Capacities up to 84 Terabytes!
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