The overview of the RAID creation process for the Ubuntu Server / mdadm / Webmin combination is similar to the one used in FreeNAS. Here is the outline, with the appropriate Webmin modules referenced (including links to the online documentation pages):
- Partition Disks [Hardware > Partitions on Local Disks]
- Create Disks Filesystem [Hardware > Partitions on Local Disks]
- Create the RAID device [Hardware > Linux RAID]
- Create the RAID device filesystem [Hardware > Linux RAID]
- Create the Mount directory [Others > File Manager]
- Mount the RAID device [System > Disk and Network Filesystems]
- Configure File Sharing [Servers > Samba Windows File Sharing]
Note: If you don't see the Linux RAID module in the Webmin left-hand menu, try clicking Refresh Modules.
1- Partition Disks
You start by creating a Linux RAID partition on each of the disks that will be used in the array. Go to the Hardware > Partitions on Local Disks page, click on the drive name, then on Add primary partition on the next page to reach the screen shown in Figure 2. Select Linux RAID from the drop-down menu and click the Create button. Repeat for the other drive(s).
Figure 2: Partitioning a disk for RAID
2- Create Drive Filesystem
Now you need to create a filesystem (format) each drive. Click the disk name again to reach the Edit Partition screen (Figure 3), select New Linux Native (ext3) and click the Create Filesystem button.
Figure 3: Creating a filesystem on each drive
Your screen will then look something like Figure 4. Repeat for the other drive(s).
Figure 4: Drive filesystem created
3- Create RAID Device
The formatted drives now must be configured into a Linux RAID device. Go to the Hardware > Linux RAID menu and use the drop-down to select the array type. Figure 5 shows a RAID0 array being created.
Figure 5: Creating a RAID0 RAID device
After clicking the Create RAID device of level button, you should see a screen like Figure 6. If the Partitions in RAID section does not appear, you should try rebooting the server since sometimes new partitions are not recognized until reboot.
Once you get the Partitions in RAID section to appear, select the desired partitions and click the Create button. Note that I set the Chunk size to 32 kB, based on this recommendation.
Figure 6: RAID device creation
If all goes well, your screen will look like Figure 7.