Resync raid drives

[Graham Leggett]

Chris Mason wrote:

> How do I resync them? There doesn't seem to be much literature out there on
> this that is current.

raidhotadd can be used to add the drive that's dropped out of the array 
back into the array.

No need to shut machine down or unmount the filesystem, it's better to 
keep the filesystem mounted so there is no doubt as to which data (the 
first or the second drive) is most current.

After using raidhotadd, a cat /proc/mdstat should show the mirror being 
rebuilt, which may take a while depending on drive size.

Regards,
Graham
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