Disks and partitions
LVM
Create new physical volume, volume group and logical group. Mount it to freshly created directory. Add to fstab for automatic mount during boot process.
# apt install lvm2
dnf install lvm2
hostname
export host="$(hostname)"
lsblk
export dev="/dev/sdb"
export size="149.9G"
# export fs="ext4"
export fs="xfs"
pvcreate ${dev}
vgcreate vg-${host}-data ${dev}
lvcreate -L ${size} -n lv-${host}-data vg-${host}-data
lvscan
mkfs.${fs} /dev/vg-${host}-data/lv-${host}-data
mkdir -p /mnt/${host}-data
mount /dev/vg-${host}-data/lv-${host}-data /mnt/${host}-data
df -h
#TODO: add into /fstab with oneliner
echo "add me to fstab"
mount | grep ${host}
nano /etc/fstab
# /dev/mapper/vg--host--data-lv--host--data /mnt/host-data ext4 defaults 0 1
systemctl daemon-reload
# when possible, test VM restart to ensure disk will be mounted
shutdown -r now
NFS export
Mount it to freshly created directory. Add to fstab for automatic mount during boot process.
Preparations:
sudo su
dnf install \
nfs-utils
Configure
# vi /etc/idmapd.conf
# [General]
# Verbosity = 0
# Domain = (domain)
# systemctl daemon-reload
# systemctl restart rpcbind
Allow network connectivity:
For Redhat family:
firewall-cmd --list-all
firewall-cmd --permanent --add-service=nfs
firewall-cmd --reload
firewall-cmd --list-all
For Debian family:
ufw status
ufw allow nfs
ufw enable
Check connecivity
Decide which declaration will be used: FQDN or IP address (depending on situation and purpose).
export src_host="(source host)"
ping ${src_host}
showmount -e ${src_host}
Verify that needed export is listed in the output and set a variable:
export src_export="(name of exported directory)"
When we are mounting shared network drive, concept "one-to-many". The shared storage must be identified in mount table by source host and exported path in the hierarchial order. This will facilitate of adding additional mounts from the same host. Preparations are as follows:
export dir="/mnt/${src_host}/${src_export}/"
echo ${dir}
read -p "Correct?"
mkdir -p ${dir}
ls -la ${dir}
Skip this, if you created directory using previous (one-to-many) concept.
Create local directory where a NFS export will be mounted. Naming used here comes from the name of attached disk to the VM (usually). To clarify, that it is a data disk, -data suffix is added. This is concept "one-to-one", which mean that the disk will be mounted only on single host.
export host="$(hostname -s)"
export dir="/mnt/${host}-data/"
echo ${dir}
mkdir -p ${dir}
If/when there is a need to use mounted resource on different machines, consider creating symbolic links. This will be useful while configuring the applications' configurations. In my case, I shall mount NFS export for Nextcloud application (ncp1 = NextCloud Production, 1st environment), change it to whatever you need. Do not worry about double forward slashes, shell interpreter will ignore them and shrink to a single slash.
export symlink="/mnt/ncp1"
ln -s ${dir} ${symlink}
ls -la ${symlink}
should end up like this:
lrwxrwxrwx. 1 root root 21 Apr 29 13:37 /mnt/ncp1 -> /mnt/(src_host)/(src_export)
and double-check mountpoint and free disk space
df -h ${symlink}
As we can see, we are still 'on local drive', because nothing is mounted yet.
Before mounting the export, check where target directory is mounted, it should be mounted on the root / and it should be empty.
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/ol-root 99G 8.2G 91G 9% /
ls -la ${dir}
total 0
drwxr-xr-x. 2 root root 6 Apr 29 13:56 .
drwxr-xr-x. 3 root root 18 Apr 29 13:56 ..
Finally, check variables and mount the export.
echo ${src_host}
echo ${src_export}
echo ${dir}
read -p "Sure to process?"
mount -t nfs4 -o nfsvers=4 ${src_host}:${src_export} ${dir}
mount | grep nfs
Check again
df -h ${dir}
ls -la ${dir}
Mounting should be presented as IP address. Exported path should be mounted in the correct destination. For example:
df -h ${dir}
Filesystem Size Used Avail Use% Mounted on
Filesystem Size Used Avail Use% Mounted on
10.x.x.x:/ifs/data/ARCHAZ/NCFS 1.0T 0 1.0T 0% /mnt/10.x.x.x/(src_export)
Let's add to new mounting point tofstab to automatically mount on the system boot:
cat /etc/fstab
echo "${src_host}:${src_export} ${dir} nfs4 nfsvers=4,defaults,_netdev,rw,sec=sys 0 0" | tee -a /etc/fstab
tail -n5 /etc/fstab
systemctl daemon-reload
Umount and check automatic mounts, simulating restart.
umount ${dir}
mount | grep nfs
read -p "Umounted?"
mount -aF
mount | grep nfs
df -h ${dir}
Content
Check for permissions to the destination directory
namei -mo ${dir}
Try to write to the destination
touch ${dir}/test.md
ls -latr ${dir}
When possible, test VM restart to ensure disk will be properly mounted, simulating real restart.
uptime
shutdown -r now
uptime
mount | grep nfs
To troubleshhot, enable RPC NFS logging. Tail the log:
rpcdebug -m nfsd -s a
tail -f /var/log/messages
To rtroubleshoot NFS, increase verbosity:
cat /proc/sys/sunrpc/nfsd_debug
cat /proc/sys/sunrpc/nfs_debug
echo 10 > /proc/sys/sunrpc/nfs_debug
Disable logging
rpcdebug - nfsd -c
In case, RPC bind is not possible, let configure operating system not to check and match user accounts bindinds. Please, acknowledge, that this will effect permissions changes.
# for Redhat Linux
sysctl -w nfs.nfs4_disable_idmapping=1
# for Oracle Linux
cat /sys/module/nfs/parameters/nfs4_disable_idmapping
echo "Y" > /sys/module/nfs/parameters/nfs4_disable_idmapping
nfsidmap -c
For permanent
# for Redhat Linux
echo "nfs.nfs4_disable_idmapping=1" | tee -a /etc/sysctl.d/99-nfs-disable-idmapping.conf
sysctl --system
# for Oracle
echo "options nfs nfs4_disable_idmapping=1" | tee -a /etc/modprobe.d/nfs.conf
dracut -f
shutdown -r now
Check permissions are not assigned to nobody:nobody anymore
namei -mo /mnt/ncp/