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I'm looking for a way to replicate a all changes on a filesystem between two disks in a master->slave setup. One of the disks is much faster for reads, so I would like to direct all reads to this real disk for performance reasons; is it possible to do this with Linux software RAID? Is there a better approach?

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up vote 4 down vote accepted

man mdadm:

   -W, --write-mostly

subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.

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Thanks, that's what I was looking for. – El Yobo Jan 30 '11 at 21:49

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