6.14. Changing the number of images in an existing RAID1 device
You can change the number of images in an existing RAID1 array, similar to the way you can change the number of images in the implementation of LVM mirroring.
When you add images to a RAID1 logical volume with the lvconvert command, you can perform the following operations:
- specify the total number of images for the resulting device,
- how many images to add to the device, and
- can optionally specify on which physical volumes the new metadata/data image pairs reside.
Procédure
Display the LVM device my_vg/my_lv, which is a 2-way RAID1 array:
# lvs -a -o name,copy_percent,devices my_vg LV Copy% Devices my_lv 6.25 my_lv_rimage_0(0),my_lv_rimage_1(0) [my_lv_rimage_0] /dev/sde1(0) [my_lv_rimage_1] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sde1(256) [my_lv_rmeta_1] /dev/sdf1(0)Metadata subvolumes named
rmetaalways exist on the same physical devices as their data subvolume counterpartsrimage. The metadata/data subvolume pairs will not be created on the same physical volumes as those from another metadata/data subvolume pair in the RAID array unless you specify--allocanywhere.Convert the 2-way RAID1 logical volume my_vg/my_lv to a 3-way RAID1 logical volume:
# lvconvert -m 2 my_vg/my_lv Are you sure you want to convert raid1 LV my_vg/my_lv to 3 images enhancing resilience? [y/n]: y Logical volume my_vg/my_lv successfully converted.
The following are a few examples of changing the number of images in an existing RAID1 device:
You can also specify which physical volumes to use while adding an image to RAID. The following command converts the 2-way RAID1 logical volume my_vg/my_lv to a 3-way RAID1 logical volume, specifying that the physical volume /dev/sdd1 be used for the array:
# lvconvert -m 2 my_vg/my_lv /dev/sdd1Convert the 3-way RAID1 logical volume into a 2-way RAID1 logical volume:
# lvconvert -m1 my_vg/my_lv Are you sure you want to convert raid1 LV my_vg/my_lv to 2 images reducing resilience? [y/n]: y Logical volume my_vg/my_lv successfully converted.
Convert the 3-way RAID1 logical volume into a 2-way RAID1 logical volume by specifying the physical volume /dev/sde1, which contains the image to remove:
# lvconvert -m1 my_vg/my_lv /dev/sde1Additionally, when you remove an image and its associated metadata subvolume volume, any higher-numbered images will be shifted down to fill the slot. Removing
lv_rimage_1from a 3-way RAID1 array that consists oflv_rimage_0,lv_rimage_1, andlv_rimage_2results in a RAID1 array that consists oflv_rimage_0andlv_rimage_1. The subvolumelv_rimage_2will be renamed and take over the empty slot, becominglv_rimage_1.
Vérification
View the RAID1 device after changing the number of images in an existing RAID1 device:
# lvs -a -o name,copy_percent,devices my_vg LV Cpy%Sync Devices my_lv 100.00 my_lv_rimage_0(0),my_lv_rimage_1(0),my_lv_rimage_2(0) [my_lv_rimage_0] /dev/sdd1(1) [my_lv_rimage_1] /dev/sde1(1) [my_lv_rimage_2] /dev/sdf1(1) [my_lv_rmeta_0] /dev/sdd1(0) [my_lv_rmeta_1] /dev/sde1(0) [my_lv_rmeta_2] /dev/sdf1(0)
Ressources supplémentaires
-
The
lvconvert(8)man page
