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didiw 01-02-2011 05:38 AM

Growing (really grow) a raid1 (mdadm --grow)

I need to increase a RAID1. I followed a post in another forum which told the following actions:
  1. do a backup
  2. remove on of the raid devices from the raid (mdadm -f ...; mdadm -r ...)
  3. increase the partition with the removed raid device
  4. add it again to the raid
  5. wait till syncing is finished
  6. repeat steps 2-5 for the other device
  7. remove the write-intent bitmap (mdadm -G /dev/mdX --bitmap=none)
  8. mdadm -G /dev/mdX --size=max
  9. mdadm --wait /dev/mdX
  10. mdadm -G /dev/mdX --bitmap=internal
Everything works until step 8. If I do a mdadm --detail /dev/mdX after it, the raid1 still has the same size as before.
What is wrong in that?
I even did that under a rescue system, because the raid1 is where my real /usr is. From reading about growing a raid 1 I got the impression, that it should be doable even in a running system.

Thank you for your answers.

Best regards and a happy new year


gb2312 01-20-2011 05:39 PM

I did similar steps (without disk repartitioning --- raid was using only part of the disk initially)
and it worked. Might be because raid/md module doesn't know the partition size changed.

* What's the error after step 8?
* Have you tried --size=NUMBER?
* Could you restart the raid before step 8?

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