RE: mdadm break / restore soft mirror

quoted

Proposed solution is to use software raid mirror.  Before backup starts,

quoted

break the soft mirror unmount and backup partition

I use this method for backup once a week.

One challenge is drives aren't great at steaming data quickly (for the resync)

while also doing a lot of random access. Having a little extra redundancy (think

3 or more drives in the RAID-1) can really help.

quoted

If you can be certain that the device that you break out of the mirror

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is never altered, then you could add an internal bitmap while the

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array is split and the rebuild will go much faster.

When the device is split from the mirror it will only be read as a raw device by the backup

software (NetBackup) and not actually mounted during the process so it really shouldn't be

modified in anyway at all.

Also during the backup window files will only be being created on remaining device (reports pdf's) so random access shouldn't be a problem either.



How do I create the internal bitmap?  man mdadm didn't shed any light and my brief excursion into google wasn't much more helpful.



The version I have installed is mdadm-1.12.0-5.i386 from RedHat which would appear to be way out of date!



Thanks for you help,

Brett

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