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Our pilot 24-disk system could for example be organized as follows:
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Our pilot 24-disk system could for example be organized as follows:
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* Optimized for storage capacity:
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(here M x (N + R) also written as MxNrR means: M stripes of N data disks plus R reserve disks (mirror or parity))
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* 1 x (21 +3) (meaning '''1''' pool consisting of '''21''' data disks and '''3''' disks for redundancy), abbreviated as 1x21r3
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* 4 x (5 + 1) - 4x5r1
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| setup | abbreviation | optimized for |
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* Optimized for stream write:
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|---|---|---|
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* 8 x (2 + 1) - 8x2r1
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| 1 x (21 + 3) | 1x21r3 | capacity |
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* 4 x (4 + 2) - 4x4r2
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| 4 x (5 + 1) | 4x5r1 | capacity, stream read |
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* 12 x (1 + 1) - 12x1r1
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| 8 x (2 + 1) | 8x2r1 | stream write, random read |
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* Optimized for stream read:
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| 4 x (4 + 2) | 4x4r2 | stream write, stream read |
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* 12 x (1 + 1) - 12x1r1
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| 12 x (1 + 1) | 12x1r1 | stream write, stream read, random read |
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* 4 x (4 + 2) - 4x4r2
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* 4 x (5 + 1) - 4x5r1
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* Optimized for random read:
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* 12 x (1 + 1) - 12x1r1
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* 8 x (2 + 1) - 8x2r1
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To calculate the usable space simply multiply the number of data disks by the capacity of a single HDD, e.g. for a 4 x (5 + 1) setup (4x5r1), one has 4*5=20 data disks and thus 240TByte usable capacity - assuming 12TByte disks. In reality, due to differences of calculating/displaying values, base1000 versus base1024 the real net capacity may be different by a few percent.
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To calculate the usable space simply multiply the number of data disks by the capacity of a single HDD, e.g. for a 4 x (5 + 1) setup (4x5r1), one has 4*5=20 data disks and thus 240TByte usable capacity - assuming 12TByte disks. In reality, due to differences of calculating/displaying values, base1000 versus base1024 the real net capacity may be different by a few percent.
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