Rename and Remount LVM Logical Volume

A usual scenario where rename and remount of LVM logical volume are needed, is when you install a box with a CentOS, and use the default LVM based partitioning scheme. This scheme will take 50G for your / partition, and the rest will be allocated to your /home, which is not practical. In this example, we will be remounting logical volume originally mounted to /home, to /var/lib/elasticsearch, renaming it along the way.

The original partition scheme 

# df -Th

Filesystem                   Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root          xfs        50G  3.0G   48G   6% /

/dev/sda1                    xfs      1014M  179M  836M  18% /boot

/dev/mapper/cl-home xfs       965G   42G  924G   5% /home

Stop the service that might be using the partition that we are going to change

# systemctl stop elasticsearch

Rename the original directory to other name

# mv /var/lib/elasticsearch /var/lib/elasticsearch-old

Create a new directory to replace the one we already renamed above

# mkdir /var/lib/elasticsearch

Unmount /home

# umount /home

Check the name of volume group and logical volume

# lvs

Rename the logical volume to the one we desired. This is totally optional. You can use -t flag to test out the renaming process before proceeding

# lvrename -t cl home elasticsearch

# lvrename cl home elasticsearch

Change /etc/fstab to reflect on the new logical volume name and mount point. Test it out without the  -i option, before permanently make the change using the -i option

# sed 's/cl-home/cl-elasticsearch/g;s/\/home/\/var\/lib\/elasticsearch/g' /etc/fstab

# sed -i 's/cl-home/cl-elasticsearch/g;s/\/home/\/var\/lib\/elasticsearch/g' /etc/fstab

Mount it

# mount -a

Check to see if your new directory and logical volume mounted properly

# df -Th

Filesystem                   Type      Size  Used Avail Use% Mounted on

/dev/mapper/cl-root          xfs        50G  3.0G   48G   6% /

/dev/sda1                    xfs      1014M  179M  836M  18% /boot

/dev/mapper/cl-elasticsearch xfs       965G   42G  924G   5% /var/lib/elasticsearch

Move the content of /var/lib/elasticsearch to /home

# mv /var/lib/elasticsearch/* /home

Move the content of /var/lib/elasticsearch-old to /var/lib/elasticsearch

# mv /var/lib/elasticsearch-old/* /var/lib/elasticsearch

Remove /var/lib/elasticsearch-old

# rmdir /var/lib/elasticsearch-old

Set proper permission for /var/lib/elasticsearch

# chmod 750 -R /var/lib/elasticsearch

# chown -R elasticsearch.elasticsearch /var/lib/elasticsearch

Start your service

# systemctl start elasticsearch

Done.

Unmounting stuck nfs mounts

This usually happened when the nfs server is down, you cannot umount the nfs mount, because the system will say "not found or server not reachable"

$ sudo umount /opt/logs/production

umount.nfs: nfs.local:/var/lib/backup: not found / mounted or server not reachable

umount.nfs: nfs.local:/var/lib/backup: not found / mounted or server not reachable

To fix this, you need to force mount it with lazy flag:

$ sudo umount -f -l /opt/logs/production

where -f is to do force unmount, and -l is for lazy unmounting. From man:
"Lazy  unmount.  Detach  the  filesystem from the filesystem hierarchy now, and cleanup all references to the filesystem as soon as it is not busy anymore."

That's all folks.