Category: mdadm

mdadm replace smaller disks with larger ones 0

mdadm replace smaller disks with larger ones

I was recently asked on the Ubuntuforums how to replace (3) 1TB drives in an mdadm one at a time. Here’s a quick writeup of the process.


Increasing the size of mdadm RAID1 disks

Do you have a couple tiny disks in a RAID1 array in mdadm and want to upgrade them with newer or larger disks? Here’s how to do it. I did this test on Ubuntu 11.10.


mdadm auto-read-only

If you’ve used mdadm for a while, you may have come across a situation where your array’s status says auto-read-only. If you see this, there’s a very easy way to fix it.


mdadm RAID5 to RAID6 migration

mdadm makes raid management, even tasks that seem like they could be very complicated very easy. The following demonstrates setting up a (5) disk RAID5 array, and then migrating to a (10) disk RAID6 array.


RAID50 mdadm

The following is how to setup a RAID50 array in mdadm. I would suggest using a RAID6 array in it’s place, but this is for demonstration purposes.


Recovery from a multiple disk failure with mdadm

If you lose more disks than you have parity to protect you from data loss, then you’re array is gone. But, quite often you get a temporary failure of several disks at once (bad cable, or failed HBA); afterwards the RAID superblocks are out of sync and you can no longer start your RAID array. Here’s a couple ways to try to get it working again.


Adding an extra disk to an mdadm array

One of the advantages of software RAID is the flexibility it gives you, that would normally only be available from high end (expensive) RAID cards. This includes the ability to grow an existing array (only for certain RAID levels), which means if you run out of space you can easily plug in a new drive and keep going.