• RAID1 is a bit more tricky. First, you will be asked to enter the number of active devices and the number of spare devices which will form the MD. Next, you need to select from the list of available RAID partitions those that will be active and then those that will be spare. The count of selected partitions must be equal to the number provided earlier. Don’t worry. If you make a mistake and select a different number of partitions, debian-installer won’t let you continue until you correct the issue. 

• RAID5 has a setup procedure similar to RAID1 with the exception that you need to use at least three active partitions. 

• RAID6 also has a setup procedure similar to RAID1 except that at least four active partitions are required. 

• RAID10 again has a setup procedure similar to RAID1 except in expert mode. In expert mode, debian-installer will ask you for the layout. The layout has two parts. The first part is the layout type. It is either n (for near copies), f (for far copies), or o (for offset copies). The second part is the number of copies to make of the data. There must be at least that many active devices so that all of the copies can be distributed onto different disks. 

It is perfectly possible to have several types of MD at once. For example, if you have three 200 GB hard drives dedicated to MD, each containing two 100 GB partitions, you can combine the first partitions on all three disks into the RAID0 (fast 300 GB video editing partition) and use the other three partitions (2 active and 1 spare) for RAID1 (quite reliable 100 GB partition for /home ). 

After you set up MD devices to your liking, you can Finish mdcfg to return back to the partman to create filesystems on your new MD devices and assign them the usual attributes like mountpoints. 

## 6.3.3.5. Configuring the Logical Volume Manager (LVM) 

If you are working with computers at the level of system administrator or “advanced” user, you have surely seen the situation where some disk partition (usually the most important one) was short on space, while some other partition was grossly underused and you had to manage this situation by moving stuff around, symlinking, etc. 

To avoid the described situation you can use Logical Volume Manager (LVM). Simply said, with LVM you can combine your partitions ( physical volumes in LVM lingo) to form a virtual disk (so called volume group ), which can then be divided into virtual partitions ( logical volumes ). The point is that logical volumes (and of course underlying volume groups) can span across several physical disks. 

Now when you realize you need more space for your old 160GB /home partition, you can simply add a new 300GB disk to the computer, join it with your existing volume group and then resize the logical volume which holds your /home filesystem and voila — your users have some room again on their renewed 460GB partition. This example is of course a bit oversimplified. If you haven’t read it yet, you should consult the LVM HOWTO (http://www.tldp.org/HOWTO/LVM-HOWTO.html). 

LVM setup in debian-installer is quite simple and completely supported inside partman . First, you have to mark the partition(s) to be used as physical volumes for LVM. This is done in the Partition settings menu where you should select Use as: −→ physical volume for LVM . 

When you return to the main partman screen, you will see a new option Configure the Logical Volume Manager . When you select that, you will first be asked to confirm pending changes to the partition table (if any) and after that the LVM configuration menu will be shown. Above the menu a summary of the LVM configuration is shown. The menu itself is context sensitive and only shows valid actions. The possible actions are: 

