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Tim
Asked: 2009-12-20 00:30:49 +0800 CST

Remove second RAID6 drive during resync from first failure?

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I have a RAID6 comprised of five 1TB drives in good working order. I'd like to redistribute the array differently in my system (change the drive distribution over controller cards). I pulled the first drive and placed it where I want it; now I just have one drive left to move. Since it's a RAID6, it should have two-drive redundancy; does that extend to the time during a resync? Can I pull the second drive, even though the array is still resyncing to the first moved drive? If so, will I be able to restart the resync over both moved drives simultaneously?

raid

2 Answers

  1. Best Answer

    For a RAID6 array you have to be able to do this, you are simply pushing the array to deal with a second drive failure which is precisely what RAID 6 is for.

    I wouldn't do this on a production system though. The main reason for choosing RAID6 is that you are paranoid about the probability of a single (additional) drive failure or single read failure during the rebuild process. By exercising a RAID6 double drive failure scenario you are putting your array in a condition where a genuine single drive failure or read failure will kill it. That would be a risk I'd rather not take for an array where I thought RAID 6 was necessary in the first place. If the performance hit of the rebuild process is not killing you I'd recommend letting the first resync complete and then move the second drive, that way your system remains protected throughout.

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  2. With the R6-capable controllers I'm familiar with yes you could pull the drive during rebuild, of course you don't say what controller you're using but I'd be >90% happy to do what you're trying with any.

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