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As per the title, what are the pros and cons of using the "Automatically rebuild RAID mirror sets" option when creating a software RAID in Disk Utility on Mac OS X (in my case, a mirrored set)?

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up vote 2 down vote accepted

The diskutil man page (OS X 10.6) says:

AutoRebuild - If true, the system attempts to rebuild degraded mirrored volumes automatically. When looking for devices for rebuild, AppleRAID first looks for hot spares and then degraded members. Use a value of "1" for true and "0" for false.

I think it would not be desirable to rebuild the mirror using a disk marked degraded, so you might consider not using AutoRebuild if you don't have a hot spare.

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Perhaps this site has some good info for you?

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I saw that page before I posted here, but it doesn't really give much information -- especially not cons. – Shaggy Frog Aug 18 '10 at 17:21
What cons did you think there'd be to automatically rebuilding the RAID set if it's broken? Unless you want to manually force a rebuild, I suppose. – Bart Silverstrim Aug 18 '10 at 17:59
If you're asking me "What cons did you think there'd be", you have to start over again at the start. I'm not assuming any pros or cons to this feature... that's exactly the point of my question! – Shaggy Frog Aug 19 '10 at 1:04
I was asking what you were worried about, since most hardware RAIDs automatically rebuild when a drive is replaced or something goes wrong. Or they attempt to and log errors if something happens. The software version may have it because it's actually a front-end to a command line tool. Auto-rebuilding should mean less maintenance on your part after a crash. Unless someone chimes in, I don't know of any drawback to using it. – Bart Silverstrim Aug 19 '10 at 11:31

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