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On 24-Feb-14 7:27, Facundo Curti wrote: |
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> n= number of disks |
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> |
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> reads: |
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> raid1: n*2 |
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> raid0: n*2 |
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> |
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> writes: |
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> raid1: n |
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> raid0: n*2 |
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> |
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> But, in real life, the reads from raid 0 doesn't work at all, because if |
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> you use "chunk size" from 4k, and you need to read just 2kb (most binary |
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> files, txt files, etc..). the read speed should be just of n. |
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Definitely not true. Very rarely you need to read just one small file. |
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Mostly you need many small files (i.e. compilation) or a few big files |
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(i.e. database). I do not know what load you expect, but in my case |
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raid0 (with SSD) gave me about twice the r/w speed on heavily-loaded |
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virtualization platform with many virtual machines. And not only speed |
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is higher, but also IOPS are splitted to two disks (nearly doubled). |
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I did some testing with 2xSSD/512GB in raid1, 2xSSD/256GB in raid0 and |
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3xSSD/256GB in raid5 (I used 840/pro SSD with quite good HW-controller |
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but I think with mdadm it might be similar). Raid0 was way ahead of |
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other two configurations in my case. |
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Finally I went for 4xSSD/256GB in raid10 as I needed both speed and |
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redundancy... |
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Jarry |
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-- |
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