Scope/Description
- This article will show how to ensure mdadm raids built on rbd will mount on boot.
- Due to the order of the linux boot process, mdadm devices built with rbd’s will not be assembled on boot time. This article provided the solution using a systemd service.
Prerequisites
- RBD images mapped and configured for auto mapping on boot.
- mdadm array created.
Steps
Creating mdadm configuruation file
- Create mdadm config directory if not already created
[root@client ~]$ mkdir /etc/mdadm
- Create mdadm.conf file if not alreay created
- Careful not to make duplicated entries !
[root@client ~]$ mdadm --examine --scan >> /etc/mdadm/mdadm.conf
- Create md-rbd.conf file
- Change the varibles accordingly to fit your environment
[root@client ~]$ cat > /etc/mdadm/md-rbd.conf <<EOF # MDADM device name MD_DEVICE=/dev/md0 # Mount point of RBD mdadm raid MOUNT_POINT=/mnt/data EOF
Creating systemd service file
- Create systemd service file, “md-rbd-assemble.service”
[root@client ~]$ cat > /usr/lib/systemd/system/md-rbd-assemble.service <<EOF [Unit] Description=mdadm assemble rbd devices ConditionPathExists=/etc/mdadm/mdadm.conf ConditionPathExists=/etc/mdadm/md-rbd.conf After=rbdmap.service [Service] EnvironmentFile=-/etc/mdadm/md-rbd.conf Type=oneshot RemainAfterExit=yes ExecStart=/usr/bin/md-rbd-assemble $MD_DEVICE $MOUNT_POINT [Install] WantedBy=multi-user.target EOF
- Create assemble-rbd-md script and past the below into the file
[root@client ~]$ touch /usr/bin/md-rbd-assemble #!/bin/bash MD_DEVICE=$1 MOUNT_POINT=$2 mdadm --assemble $MD_DEVICE mount -t xfs $MOUNT_POINT
- Mark it executable
[root@client ~]$ chmod +x /usr/bin/md-rbd-assemble
- Add entry to fstab for md mount
- Make sure md device and mountpoint are correct for your environment
[root@client ~]$ echo "/dev/md0 /mnt/data xfs defaults,noatime,nofail 0 0" >> /etc/fstab
- Enable md-rbd-assemble.service
[root@client ~]$ systemctl enable md-rbd-assemble
- Reboot and verify that mdadm is started and mounted
Verification
Troubleshooting
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