Create a RAID device with Cockpit
Log into Cockpit.
Make sure you have at least kernel 4.0.0-0.rc4.git1.3. Earlier kernels have this bug and this test is known to fail.
Make sure you have at least four unused block devices. If you don't have enough real ones (such as USB sticks), you can make loopback devices like so:
# dd if=/dev/zero of=/disk1.img bs=1M count=100 # losetup -f /disk1.img # dd if=/dev/zero of=/disk2.img bs=1M count=100 # losetup -f /disk2.img # dd if=/dev/zero of=/disk3.img bs=1M count=100 # losetup -f /disk3.img # dd if=/dev/zero of=/disk4.img bs=1M count=100 # losetup -f /disk4.img
These devices should imediately show up in Cockpit in the "Other Devices" section.
Make sure that these devices contain only zeros. Otherwise Cockpit might assume that they are in use for something and will not allow to use them for a new RAID device.
How to test
- Navigate to "Storage" for your machine.
- Create a RAID device of level "raid5" out of three of the four devices.
- Format the device as "ext4" and mount it on "/data".
- Remove one of the disks from the RAID device and observe that the RAID device is now "degraded".
- Add the forth disks and watch the RAID device recover.
- Unmount the filesystem.
- Set the "Mount Point" of the filesystem in the "Filesystem Options" dialog to the empty string. This will remove the corresponding line from /etc/fstab. (Cockpit should do this automatically when the RAID device is deleted in the next step, but it currently does not, unfortunately.)
- Delete the RAID device.
No errors should occur.