8.10. The Linux RAID Module
This module allows you to create, format, and delete RAID arrays on your Linux system. Like the other hard-disk related modules, it can be found under the Hardware category. When you enter the module, the main page will display existing RAID devices (if any), as shown in Figure 8.4.
Figure 8.4. The Linux RAID module.
If Webmin detects that the commands used to set up RAID are missing from your system, an error message will be displayed on the main page of the module. Most Linux distributions, however, should have a package on their CD or website containing the RAID commands. A different error will be displayed if your Linux kernel has not been compiled with RAID support. In this case, you may have to recompile the kernel with RAID supported turned on.
Assuming all the necessary packages have been installed, adding a new RAID device is relatively easy. The steps to follow are:
1. | In the Partitions on Local Disks module, create a partition on each disk that you want to use for RAID. Existing partitions can also be used, as long as they do not contain any data that you do not want overwritten. A disk that is partially used for some other purpose can also have a new partition added for RAID use, although this may negate some of the performance benefits. Every partition that is going to be part of the RAID array should have its type set to Linux raid. Unless you are using linear mode, all partitions should be the same size so that space on the larger partitions is not wasted. |
2. | At this point, it may be necessary to reboot your system. Some Linux kernels can only detect new partitions at boot time. If you do not reboot and the partition is not detected, the creation of the RAID device will fail. |
3. | On the main page of the module, select the RAID level that you want to use and click the Create RAID device of level button. This will take you to a form for selecting the partitions to be part of the array and other options, assuming Webmin detects at least one unused partition on your system. |
4. | The Partitions in RAID option will list all hard disk partitions that are not currently in use for possible inclusion in your RAID device. It will also list any other RAID devices that are not in use, allowing you to theoretically create an array that contains other arrays. Select all the partitions that you want to be part of your new RAID device. |
5. | The Force initialization of RAID? option should be set to Yes if any of the selected partitions have been used before for other purposes. Otherwise, the creation of the new array will fail if a filesystem is detected on any of the partitions. |
6. | Click the Create button to set up the new array. If everything is successful, you will be returned to the main page of the module, which should now include your new RAID device. |
7. | If you want to create a filesystem on the new device so that it can be mounted, click on its icon to go to the device status page. If the RAID device is to be used for virtual memory, as part of an LVM volume group or as part of another RAID array, then this is not necessary. |
8. | Select the type of filesystem you want to create from the menu at the bottom of the page and click the Create filesystem of type button. |
9. | Select any options for the new filesystem, as explained in Section 8.4 “Creating a New Filesystem”. When done, click the Create button. A page showing the progress of the new filesystem's creation will be displayed, which can take some time for large arrays. |
10. | Assuming that the formatting is successful, you can now use the Disk and Network Filesystems module to mount the new filesystem. |
Existing RAID devices that are not in use can be deleted or deactivated by clicking on their icon on the main page of the module, and pressing the Delete button. Deleting a device will cause any data stored on it to be lost forever.