Managing RAID on Linux

Existing Arrays

If you have inherited a system that already uses software RAID, you need to decide whether you’re going to continue maintaining that array or retire it and migrate the data to a new array (hardware or software). The rest of this chapter focuses on constructing new software arrays. If you plan to keep maintaining an array that already exists, read Chapter 4 and Chapter 7.

If you want to scrap an existing RAID, this section offers some advice that will help you dismantle the array. It’s vital to keep in mind that reconfiguring an array or reusing its member disks in new arrays means that existing data will be lost. So it’s very important to back up any data before proceeding.

Tip

In certain cases, it’s possible to remove a member disk without losing data on an array. For example, removing an unused spare disk from a RAID-1 or RAID-5 will not cause data loss, although it might reduce fault tolerance.

If you plan to scrap all your existing arrays and use hardware RAID, skip straight to Chapter 5; the preparatory steps in this section do not apply to that situation.

Finally, if you are experimenting with various RAID levels and plan to reuse partitions that you have already included in another array, you might need to take some additional steps before building the new array. Remember that reusing these partitions means that the data on them will be destroyed, along with your array. Furthermore, you will not be able create a new array using partitions that are members of an ...