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On Mittwoch 10 Februar 2010, Iain Buchanan wrote: |
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> On Wed, 2010-02-10 at 07:31 +0100, Volker Armin Hemmann wrote: |
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> > On Mittwoch 10 Februar 2010, Iain Buchanan wrote: |
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> > > so long as you didn't have any non-detectable disk errors before |
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> > > removing the disk, or any drive failure while one of the drives were |
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> > > removed. And the deterioration in performance while each disk was |
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> > > removed in turn might take more time than its worth. Of course RAID 1 |
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> > > wouldn't suffer from this (with >2 disks)... |
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> > |
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> > Raid 6. Two disks can go down. |
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> |
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> not that I know enough about RAID to comment on this page, but you might |
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> find it interesting: |
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> http://www.baarf.com/ |
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> specifically: |
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> http://www.miracleas.com/BAARF/RAID5_versus_RAID10.txt |
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|
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and that is very wrong: |
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|
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but if |
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the drive is going these will not last very long and will run out and SCSI |
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does NOT report correctable errors back to the OS! Therefore you will not |
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know the drive is becoming unstable until it is too late and there are no |
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more replacement sectors and the drive begins to return garbage. [Note |
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that the recently popular IDE/ATA drives do not (TMK) include bad sector |
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remapping in their hardware so garbage is returned that much sooner.] |
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|
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so if the author is wrong on that, what is with the rest of his text? |
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And why do you think Raid6 was created? |
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With Raid6 one disk can fail and another return garbage and it is still able |
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to recover. |
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Another reason to use raid6 is the error rate. One bit per 10^16 sounds good - |
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until you are fiddling with terabyte disks. |
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|
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>Conclusion? For safety and performance favor RAID10 first, RAID3 second, |
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RAID4 third, and RAID5 last! |
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|
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and that is just mega stupid. You can google. Or just go straight to |
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wikipedia, if you don't know why. |