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On Friday 06 October 2006 17:30, Christian Spoo wrote: |
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> I need to set up a RAID box of about 470GB disk space accessible via |
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> GBit LAN. |
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> |
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> The whole thing should have good performance but must be reliable as |
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> well. Which RAID mode would you recommend, 5, 0+1 or maybe any other? |
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> How about the time needed for rebuilding such arrays in case of disk |
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> failure? |
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Firstly, forget 0+1, use RAID10. |
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Define "good performance". Reads or writes? |
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RAID5 is fast for reads, slow for writes, and you lose the capacity of 1 disk. |
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RAID10 is *fast* for reads *and* writes, but you lose the capacity of half |
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your disks. |
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RAID5 can live with the failure of one drive, but takes a large performance |
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hit and all your redundancy is gone until a new one is synced up which is |
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hard and time consuming to do. |
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RAID10 can, in theory, lose half of the disks and continue with little to no |
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slow down. Rebuilds are easier than RAID5 as it's a straight bit for bit |
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copy. |
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RAID6 adds a second disk worth of redundancy, but slows writes down further. |
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As a bad benchmark I had to rebuild a 4 200GB disk RAID5 array the other |
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evening on a P3 1400, took ~140minutes. |
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On at least 2 occasions I've had another disk die while doing a RAID rebuild, |
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the stress was too much for it, for this reason I won't use RAID5 again |
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unless there is a very good reason for it (i.e. need for redundancy is |
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minimal, and space is more important). |
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-- |
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Mike Williams |
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-- |
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