Chapitre 6. Configuring RAID logical volumes
You can create, activate, change, remove, display, and use LVM Redundant Array of Independent Disks (RAID) volumes.
6.1. RAID logical volumes
Logical volume manager (LVM) supports Redundant Array of Independent Disks (RAID) levels 0, 1, 4, 5, 6, and 10. An LVM RAID volume has the following characteristics:
- LVM creates and manages RAID logical volumes that leverage the Multiple Devices (MD) kernel drivers.
- You can temporarily split RAID1 images from the array and merge them back into the array later.
- LVM RAID volumes support snapshots.
Other characteristics include:
- Clusters
RAID logical volumes are not cluster-aware.
Although you can create and activate RAID logical volumes exclusively on one machine, you cannot activate them simultaneously on more than one machine.
- Subvolumes
When you create a RAID logical volume (LV), LVM creates a metadata subvolume that is one extent in size for every data or parity subvolume in the array.
For example, creating a 2-way RAID1 array results in two metadata subvolumes (
lv_rmeta_0andlv_rmeta_1) and two data subvolumes (lv_rimage_0andlv_rimage_1). Similarly, creating a 3-way stripe and one implicit parity device, RAID4 results in four metadata subvolumes (lv_rmeta_0,lv_rmeta_1,lv_rmeta_2, andlv_rmeta_3) and four data subvolumes (lv_rimage_0,lv_rimage_1,lv_rimage_2, andlv_rimage_3).- Integrity
- You can lose data when a RAID device fails or when soft corruption occurs. Soft corruption in data storage implies that the data retrieved from a storage device is different from the data written to that device. Adding integrity to a RAID LV reduces or prevent soft corruption. For more information, see Creating a RAID LV with DM integrity.
