LVs and RAID management

1. How to mount RAID after boot from USB stick?

a.  detect multiple paths to devices for fail-over or performance reasons and coalesces them

[root@localhost ~]#Multipath

b. scan all disks for volume groups and rebuild caches
[root@localhost ~]#vgscan

c. active the VG (In other words, makes  the  logical  volumes known/unknown to the kernel)
[root@localhost ~]#vgchange -a y

d. create the mount point

[root@localhost ~]#mkdir -p  /var/mnt/local/localimg-cla-0
[root@localhost ~]#mkdir -p /var/mnt/local/localimg-cla-1

e. Assemble a pre-existing array

[root@localhost ~]#mdadm -A /dev/md0 /dev/VG_63/localimg_CLA-0
[root@localhost ~]#mdadm -A /dev/md1 /dev/VG_63/localimg_CLA-1

f. mount the RAID

[root@localhost ~]#mount /dev/md0  /var/mnt/local/localimg-cla-0
[root@localhost ~]#mount /dev/md1  /var/mnt/local/localimg-cla-1

g. check the filesystem usage

[root@localhost ~]# df
Filesystem           1K-blocks      Used Available Use% Mounted on
rootfs                 1037484    320648    716836  31% /
root                   1037484    320648    716836  31% /
dev                    1037484       248   1037236   1% /dev
none                   1037484       248   1037236   1% /dev
/dev/md0               5039552   2439392   2344164  51% /var/mnt/local/localimg-cla-0
/dev/md1               5039552   2167300   2616256  46% /var/mnt/local/localimg-cla-1

 

2. Create RAID with one LVs

[root@localhost ~]#mdadm -C -a -v -l1 --force -n1 /dev/md0 /dev/VG_63/localimg_CLA-0
[root@localhost ~]#mdadm -C -a -v -l1 --force -n1 /dev/md1 /dev/VG_63/localimg_CLA-1