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Linux Storage: Mount, Disks, Partitions, Filesystems, LVM, Mdadm, Swapfile, Smartmontools, NFS & Samba

3262 words·
Linux Storage Commands
Table of Contents

Mount: Fstab & Mtab
#

Overview
# 

# Mounts at system start
vi /etc/fstab

# Mount all mountpoints from fstab
mount -a


# Currently mounted
vi /etc/mtab

# List filesystem (for fstab entry)
lsblk -f

blkid
#

Blkid displays the UUID (Universally Unique Identifier), filesystem type, label, and other attributes related to disk partitions and storage devices.

Using the UUID is considered more reliable because it is unique to the filesystem and does not change, even if the disk is moved to a different port on the motherboard, or if you add another disk to the system.

# List 
sudo blkid

# Shell output:
...
/dev/mapper/debian--vg-root: UUID="272d2881-7512-4941-a25c-4ecfc9d279a8" BLOCK_SIZE="4096" TYPE="ext4"

Fstab Example:

# fstab
UUID=272d2881-7512-4941-a25c-4ecfc9d279a8 / ext4    errors=remount-ro 0 1

Pass Parameter
#

Fstab Example:

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
/dev/disk/by-uuid/62f6cdf8-2832-4120-901d-18e7e7e37d0a /boot ext4 defaults 0 1
  • Used by fsck to decide in which order filesystems are to be checked.
  • 0 The filesystem will be ignored and not checked at boot time.
  • 1 The filesystem will be checked first. This is typically used for the root filesystem, and only one filesystem should have this value to avoid potential conflicts.
  • 2 All other filesystems that should be checked.

Mount and unmount
# 

# Mount file system (from fstab)
mount /mountpoint

# Unmount file system
umount /mountpoint

# Unmount file system still in use without killing processes
umount -l /mountpoint

# Terminates processes using the file system
umount -f /mountpoint

Umount busy device
# 

# List processes that use a mountpoint
lsof +f -- /mnt/mountpoint
# or
lsof \| grep '/mountpoint'

# Kill buisy process
pkill PID

# Unmount
umount /mountpoint

Disks & Partitions
#

lsblk (List Disks)
#

List block devices:
Find devices and partitions information

Example: lsblk

sda                         8:0    0    20G  0 disk
├─sda1                      8:1    0     1M  0 part
├─sda2                      8:2    0   1.8G  0 part /boot
└─sda3                      8:3    0  18.2G  0 part
  └─ubuntu--vg-ubuntu--lv 253:0    0    10G  0 lvm  /
lsblk List disks and partitions
lsblk -f List file systems (ntfs, ext4, …)
lsblk -m Owner / Permissions
lsblk /dev/sda List partitions of specific disk

df (List Mountpoints & Filesystems)
#

Free Disk: Disk usage and filesystem information

# List mountpoints
df -h

# Shell output:
Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv   17G   11G  4.8G  70% /
/dev/sda2                          2.0G  251M  1.6G  14% /boot

# List filesystems
df -T

# Shell output:
Filesystem                        Type  1K-blocks     Used Available Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv ext4   16849712 11020688   4947772  70% /
/dev/sda2                         ext4    1992552   256672   1614640  14% /boot

fdisk
#

Fixed disk or format disk:
Create, delete, resize, and modify partitions

Example: fdisk -l

Disk /dev/sda: 20 GiB, 21474836480 bytes, 41943040 sectors
Disk model: ...
...

Device       Start      End  Sectors  Size Type
/dev/sda1     2048     4095     2048    1M BIOS boot
/dev/sda2     4096  3719167  3715072  1.8G Linux filesystem
/dev/sda3  3719168 41940991 38221824 18.2G Linux filesystem
fdisk -l List disks partitions
dfisk -l /dev/sda List partitions of specific disk

parted
# 

# Start parted for specific disk: sda
sudo parted /dev/sda

# List all partitions
sudo parted -l

# List partitions: Specific disk
sudo parted -l /dev/sda

Extend Partition
#

  • Check the disk & partition size
# List blockdevices
lsblk

# Shell output:
NAME                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda                         8:0    0   40G  0 disk
├─sda1                      8:1    0    1M  0 part
├─sda2                      8:2    0    2G  0 part /boot
└─sda3                      8:3    0   33G  0 part
  └─ubuntu--vg-ubuntu--lv 253:0    0 16.5G  0 lvm  /
  • Start parted for the specific disk
# Start parted for specific disk: sda
sudo parted /dev/sda

# List partitions
print

# Shell output:
Model: VMware, VMware Virtual S (scsi)
Disk /dev/sda: 42.9GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End     Size    File system  Name  Flags
 1      1049kB  2097kB  1049kB                     bios_grub
 2      2097kB  2150MB  2147MB  ext4
 3      2150MB  37.6GB  35.4GB

# Resize partition 3 (/dev/sda3)
resizepart 3 100%

# Quit parted
quit
  • Control the disk & partition size
# Check the parition size: List blockdevices
lsblk

# Shell output:
NAME                      MAJ:MIN RM  SIZE RO TYPE MOUNTPOINTS
sda                         8:0    0   40G  0 disk
├─sda1                      8:1    0    1M  0 part
├─sda2                      8:2    0    2G  0 part /boot
└─sda3                      8:3    0   38G  0 part
  └─ubuntu--vg-ubuntu--lv 253:0    0 16.5G  0 lvm  /
sr0                        11:0    1 1024M  0 rom
  • Extend PV & LV
# Resize PV
sudo pvresize /dev/sda3

# Resize LV and filesystem
sudo lvextend -r -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv

Filesystems
#

mkfs
# 

# Create ext4 filesystem (on disk sdb)
sudo mkfs.ext4 /dev/sdb

# Create ext4 filesystem with label
sudo mkfs.ext4 -L disk-2 /dev/sdb

# Check label: lsblk
lsblk -o NAME,FSTYPE,LABEL,MOUNTPOINT

# Check label
sudo e2label /dev/sdb

# Check label: Alternative command
sudo blkid /dev/sdb

# Shell output:
/dev/sdb: LABEL="disk-2" UUID="812b5ef6-0392-4fba-aaa9-25f7dece632f" BLOCK_SIZE="4096" TYPE="ext4"

wipefs
#

The wipefs command is used to wipe filesystems, RAID signatures, and partition tables from a device or partition.

# Wipe disk: For example sdb
sudo wipefs -a /dev/sdb
  • -a “All” remove everything

fsck
#

Check and repair filesystems.

# Open manual
man fsck

# Check a filesystem: Define disk or partition
sudo fsck /dev/sdb

# Check and repair a filesystem: Try to repair filesystem errors automatically (no prompts)
sudo fsck -a /dev/sdb

Note: Never run fsck on a mounted filesystem.

LVM
#

Overview
#

Physical Volume:
Example pvdisplay

  --- Physical volume ---
  PV Name               /dev/sda3
  VG Name               ubuntu-vg
...

Volume Groups:
Example vgs

  VG        #PV #LV #SN Attr   VSize  VFree
  ubuntu-vg   1   1   0 wz--n- 18.22g 8.22g

Logical Volumes:
Example lvs

LV        VG        Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  ubuntu-lv ubuntu-vg -wi-ao---- 10.00g

Physical Volumes
# 

# List physical volumes:
sudo pvs

# List physical volumes: Details
sudo pvdisplay

# Create physical volume
sudo pvcreate /dev/sdb

Volume Groups
# 

# List volumegroups
sudo vgs

# List volumegroups: Details
sudo vgdisplay -v

# List volumegroups: Details about specific VG (for example "debian-vg")
sudo vgdisplay debian-vg

# Create new volumegroup
sudo vgcreate vgname /dev/sdb

# Add physical volume to volumegroup
sudo vgextend vgname /dev/sdc

# Remove physical volume from group
sudo vgreduce vgname /dev/sdc

Create Logical Volume
# 

# Create LV: storage in GB
sudo lvcreate -n lvname --size 5G vgname

# Create LV: storage in GB / different notation
sudo lvcreate -n lvname -L 5G vgname

# Create LV: storage in %
sudo lvcreate -n lvname -l 100%FREE vgname

# Create ext4 Filesystem
sudo mkfs.ext4 /DEV/path/to/LV

Delete Logical Volume
# 

# Deactivate logical volume
sudo lvchange -an vgname/lvname

# Check status / verify status
sudo lvscan

# Delte LV / Remove logical volume from VG
sudo sudo lvremove vgname/lvname

Extend Logical Volume
# 

# Extend LV
sudo lvextend -l +20G /DEV/path/to/LV

# Check new size of LV
lsblk

# Extend Filesystem
sudo resize2fs -p /DEV/path/to/LV

# Check size of Filesystem
df -h

Activate / Deactive LV
# 

# Check logical volume status
sudo lvscan

# Activate logical volume
sudo lvchange -ay /dev/ubuntu-vg/esxi1-lv

# Deactivate logical volume
sudo lvchange -an /dev/vgname/lvname

Example: Extend LV & Filesystem together
#

Check available LVM storage with pvs

The output should look like this:

  PV         VG        Fmt  Attr PSize  PFree
  /dev/vda3  ubuntu-vg lvm2 a--  18.22g 8.22g

Use df -h to find dev-mapper name of the LV:

Output:

/dev/mapper/ubuntu--vg-ubuntu--lv  9.8G  7.7G  1.6G  83% /

Extend LV and filesystem together with -r option: 

# Extend LV and filesystem: For example +8GB
sudo lvextend -r -L +8G /dev/mapper/ubuntu--vg-ubuntu--lv

# Extend LV and filesystem: For example 100% of available VG storage
sudo lvextend -r -l +100%FREE /dev/mapper/ubuntu--vg-ubuntu--lv

Example: Remove LV
#

Use df -h to find dev-mapper name of LV, Output:

Filesystem                         Size  Used Avail Use% Mounted on
/dev/mapper/ubuntu--vg-ubuntu--lv  9.8G  7.7G  1.6G  83% /

Unmount and remove the logical volume:
sudo lvremove /dev/mapper/ubuntu--vg-ubuntu--lv

Don’t try with the root partition ;)


LVM Snapshot
# 

# Create LVM Snapshot: Syntax
sudo lvcreate --size [SnapshotSize] --snapshot --name [SnapshotName] [VolumeGroupName]/[OriginalLogicalVolumeName]

# Create LVM Snapshot: Example
sudo lvcreate --size 5G --snapshot --name root-snapshot debian-vg/root


# Remove the Snapshot: Syntax
sudo lvremove [VolumeGroupName]/[SnapshotName]

# Remove the Snapshot: Example
sudo lvremove debian-vg/root-snapshot

  • --size The size specified depends on the expected changes to the original volume during the snapshot’s life. It doesn’t need to be as large as the original volume unless you expect the total changes to match the original volume’s size.

  • --snapshot --name Define a name for the snapshot

Note: LVM does not directly support overwriting an existing snapshot. You have to manually remove the old snapshot before creating a new one with the same name.


Software RAID: Mdadm
#

Create RAID
#

sudo apt install mdadm Install mdadm utility
sudo mdadm --detail --scan List available RAIDS
Disks
lsblk List available block devices
mdadm --examine /dev/sdb /dev/sdc Examine disks for any existing RAID blocks
mdadm: No md superblock detected on /dev/sdb Output
mdadm: No md superblock detected on /dev/sdc Output
Create RAID
mdadm [mode] <raiddevice> [options] <component-devices> Syntax
mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sdb /dev/sdc Create RAID 1
cat /proc/mdstat Check if raid was created
watch -n1 cat /proc/mdstat Monitor building process
Verify RAID
mdadm --detail /dev/md0 Check status (active sync)
Save RAID
mdadm --detail --scan | sudo tee -a /etc/mdadm/mdadm.conf Save the Array Layout, array gets reassembled automatically at boot
update-initramfs -u Update the initramfs

Delete RAID
#

df -h Find mountpoint of RAID, for example:

/dev/md0                           7.3T  262G  6.6T   4% /mnt/raid5_md0
Unmount
umount /mnt/raid5_md0 Unmount RAID
df -h Check if RAID is unmounted
vi /etc/fstab Remove RAID mount references0
Stop RAID
mdadm --stop /dev/md0 Stop RAID
mdadm: stopped /dev/md0 Shell output
Delete RAID
mdadm --zero-superblock /dev/sdb Remove RAID metadata / configuration from disks
mdadm --zero-superblock /dev/sdc Repeat for all RAID disks
cat /proc/mdstat Check for active RAID / RAID is removed
Edit mdadm.conf
vi /etc/mdadm/mdadm.conf Remove the array definition
ARRAY /dev/md0 ... Delete the following line
Update initramfs
update-initramfs -u Save system configuration changes

Encrypt RAID
#

apt install cryptsetup Should aleady be installed
cryptsetup luksFormat /dev/md0 Format with LUKS encryption
YES Confirm to remove all data
Enter passphrase for /dev/md0 Enter passpharase
cryptsetup luksOpen /dev/md0 md0_enc Initialize encrypted volume
Enter passphrase for /dev/md0 Enter passpharase

LVM example
#

pvcreate /dev/mapper/md0_enc Create LVM PV
pvs Check PV
vgcreate md0_enc_vg /dev/mapper/md0_enc Create LVM VG
vgs Check VG
lvcreate -n md0_enc_lv1 -l 100%FREE md0_enc_vg Create LVM LV, allocate 100%
lvcreate -n md0_enc_lv1 -L 100G md0_enc_vg Create LVM LV, allocate 100G
lvs Check LV
mkfs.ext4 /dev/md0_enc_vg/md0_enc_lv1 Create ext4 filesystem
mount /dev/md0_enc_vg/md0_enc_lv1 /mnt/md0 Mount filesystem
/dev/raid1-vg1/raid1-lv1 /mnt/md0 ext4 defaults 0 0 Add entry to fstab

Restore RAID
#

Use the following Commands to gather the necessary RAID details:
lsblk List hard drive details
sudo mdadm --detail --scan List available RAIDS
cat /proc/mdstat List RAID details / drives

Note: The following commands must be conducted for all RAIDS that include a disk partition, in this ecample sdb1, sdb2, sdb3…

# Verify the RAID / disk status
sudo mdadm --detail /dev/md1

# Mark the failed drive status as failed:
sudo mdadm --manage /dev/md1 --fail /dev/sdb1

# Verify status
cat /proc/mdstat

# Remove the failed drive from RAID:
sudo mdadm --manage /dev/md1 --remove /dev/sdb1

Physically replace the failed drive

# Find new disk
`lsblk`

# Copy partition table to new disk
sudo sfdisk -d /dev/sda | sudo sfdisk /dev/sdb

#Add the new drive to the RAID array
sudo mdadm --manage /dev/md1 --add /dev/sdb

# Monitor the RAID recovery
watch cat /proc/mdstat

# Verify the RAID status
sudo mdadm --detail /dev/md1

Troubleshooting
#

I recently had the case that as a result of an unexpected power outage, followed by a faulty hard drive and server reboots, a RAID configuration changed from RAID 6 to RAID 0.

Here are the steps to solve the problem. First compare the RAID details to the RAID disk details, in my case the RAID disks had 4 RAID devices defined, but the RAID itself only 3.

mdadm --detail /dev/md0

/dev/md0:
           Version : 1.2
     Creation Time : Thu Sep  9 10:50:37 2021
        Raid Level : raid6
        Array Size : 3906758656 (3725.78 GiB 4000.52 GB)
     Used Dev Size : 1953379328 (1862.89 GiB 2000.26 GB)
      Raid Devices : 3
     Total Devices : 3
       Persistence : Superblock is persistent
...

mdadm --examine /dev/sda2

/dev/sda2:
          Magic : a92b4efc
        Version : 1.2
    Feature Map : 0x1
     Array UUID : fc3e9d73:f9fc83e6:823fa4a4:2f50be51
           Name : ubuntu-server:0
  Creation Time : Thu Sep  9 10:50:37 2021
     Raid Level : raid6
   Raid Devices : 4
...

Change the RAID Configuration:

# Stop the RAID
mdadm --stop /dev/md0

# Open MDADM Configuration File
vi /etc/mdadm/mdadm.conf

# Add the correct RAID and Device definition to the specific RAID definition
level=raid6 num-devices=6
# For Example:
ARRAY /dev/md0 metadata=1.2 name=ubuntu-server:0 UUID=fc3e9d73:f9fc83e6:823fa4a4:2f50be51 level=raid6 num-devices=4

# Assemble the RAID
mdadm --assemble --scan

# Save the changed RAID configuration to take effect at boot time
update-initramfs -u -k all

Swapfile
#

List Swapfile
sudo swapon --show List configured swap files
cat /proc/swaps List all Swapfiles
free -h List available RAM and Swap
Disable & Remove Swapfile
sudo swapoff /swapfile Disable Swapfile (with path)
sudo rm/swapfile Remove Swapfile (with path)
vi /etc/fstab Remove Swapfile entry in fstab
# /swap.img none swap sw 0 0 Comment or remove entry
Create Swapfile
sudo fallocate -l 2G /swapfile Create Swapfile (2G)
ls -lh /swapfile Verify amount of space of Swapfile
sudo chmod 600 /swapfile Change permissions / root access only
ls -lh /swapfile Verify the permissions
sudo mkswap /swapfile Mark the file as swap space
sudo swapon /swapfile Enable the Swapfile
sudo swapon --show Verify the Swapfile
Make Swap permanent / Add entry in fstab
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab Add entry

Smartmontools
#

Smartmontools allows to monitor and check the health of hard drives and SSDs.

Overview
# 

# Install Smartmontools / SmartCTL
apt install smartmontools -y

# Check Status
systemctl status smartd

# Restart Smartmontools
systemctl restart smartd


# Open Smartmontools Configuration File
vi /etc/smartd.conf


# Help: Smartmontools
man smartctl

# Help: Smartmontools Configuration File
man smartd.conf

Find Devices
# 

# List all storage devices
smartctl --scan

# List block devices (could be helpful)
ls /sys/block

Check Devices
# 

# List: Device model, serial number
smartctl -i /dev/sda

# Health Test: Outputs only Passed / Failed
smartctl -H /dev/sda

#Diagnose potential device issues
smartctl -a /dev/sda

Example
#

Example for hard drive attribute values.

smartctl -a /dev/sda | less

Watch out for the following arrtributes from the console output:

ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
...
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0
...
197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -       0

Configuration File
#

Example for Smartmontools Configuration File.

List disks with physical connection path:
ls -la /dev/disk/by-path/

# Open Smartmontools config
vi /etc/smartd.conf

# Example: Scan all Devices (not recommended)
DEVICESCAN -a

# Example: Bulk Config
DEVICESCAN -d removable -n standby -m root -M exec /usr/share/smartmontools/smartd-runner -s (S/../.././02|L/../../5/18:007)

# Example: Single Disk
/dev/disk/by-path/pci-0000:00:11.4-ata-1 -m root -M exec /usr/share/smartmontools/smartd-runner -s (S/../.././02|L/../../5/18)

Disk speed
#

The following command tests the disks read speed, the --direct option is used to bypass the kernal cache and read directly from the disk:

sudo hdparm -tT --direct /dev/sda


NFS Export
#

Installation & Status
# 

# Update package manager
sudo apt update

# Install NFS
sudo apt install nfs-kernel-server

# Check status
sudo systemctl status nfs-server

NFS Export / Shares
# 

# Edit NFS shares
sudo vi /etc/exports

# Restart NFS Server
sudo systemctl restart nfs-server

# Reload config without stopping NFS server
sudo systemctl reload nfs-server

# Re-export all NFS shares
sudo exportfs -r

Examples: Permissions
# 

# Export read only
/srv/nfs/nfs_share 192.168.60.101(ro,sync)

# Export read and write mode
/srv/nfs/nfs_share 192.168.60.101(rw,sync)

# Export with sudo permissions for NFS client
/srv/nfs/nfs_share 192.168.60.101(rw,sync,no_root_squash)

Examples: Clients
# 

# Export to all hosts
/srv/nfs/nfs_share *(sync)
/srv/nfs/k8s_share *(rw,sync,no_subtree_check,no_root_squash)

# Export to single host
/srv/nfs/nfs_share 192.168.60.101(sync)

# Export to multiple hosts
/srv/nfs/nfs_share 192.168.60.101(sync)
/srv/nfs/nfs_share 192.168.60.102(sync)
/srv/nfs/nfs_share 192.168.60.103(sync)

# Export to IP range (long & short)
/srv/nfs/nfs_share 192.168.60.101/255.255.255.0(sync)
/srv/nfs/nfs_share 192.168.60.101/24(sync)

# Export to subdomains (with wildcard)
/dump/backups *.jklug.work(sync)

NFS Mount on Client
#

Install NFS Client
# 

# Install NFS Client
sudo apt install nfs-common -y

Verify the NFS connectivity
# 

# Find the showmount bin
find / -name showmount 2>/dev/null

# Verify that the NFS server is correctly configured
/usr/sbin/showmount -e NFS-server-IP

Mount NFS Share
# 

# Create directory for NFS export
mkdir -p /mnt/mountpoint

# Mount NFS export (verbose)
mount -t nfs -vvvv IP:/srv/nfs/nfs_share /mnt/mountpoint

# Mount with specific NFS version
mount -o nfsvers=4 IP:/srv/nfs/nfs_share /mnt/mountpoint

# Mount with read only permissions
mount -o ro IP:/srv/nfs/nfs_share /mnt/mountpoint

# Auto-detect file system / default option rw
mount IP:/srv/nfs/nfs_share /mnt/mountpoint

# List all currently mounted NFS exports
mount -t nfs

# List all available NFS exports for the client
showmount -e

Note: /mnt/ is a traditional temporary mount point.

Permanently mount with fstab
# 

# Open fstab
sudo vi /etc/fstab

# Add entry for NFS share
IP:/srv/nfs/nfs_share /mountpoint nfs defaults 0 0

# Mount NFS export
sudo mount /mountpoint

Optional: Specify NFS Version
#

Open /etc/nfs.conf uncomment and define specific NFS version with “y” and “n”:

[nfsd]
# debug=0
# threads=8
# host=
# port=0
# grace-time=90
# lease-time=90
# udp=n
# tcp=y
 vers2=n
 vers3=n
 vers4=y
 vers4.0=y
 vers4.1=y
 vers4.2=y
# rdma=n
# rdma-port=20049

Samba
#

Samba Commands
apt install samba -y Install Samba
smbd --version Check version
vi /etc/samba/smb.conf Edit config
sudo service smbd restart Restart Samba service
systemctl status smbd Samba service status
systemctl start smbd Start Samba service
systemctl stop smbd Stop Samba service
systemctl enable smbd Enable service at boot
systemctl disable smbd Disable service at boot
testparm List Samba config
Samba DB Commands
smbpasswd -a username Add Samba DB user / change PW
smbpasswd -e username Enable Samba DB user
smbpasswd -d username Disable Samba DB user
smbpasswd -x username Remove Samba DB user
pdbedit -L List Samba DB users
sudo pdbedit -L | grep username Check if user exists in Samba db

Share without credentials
# 

[sharename]
   path = /share/path
   browsable = yes
   writable = yes
   guest ok = yes
   read only = no

Add the configuration to /etc/samba/smb.conf. The guest ok = yes parameter enables to access the share without credentials with writable permissions.

Share with credentials
#

Configuration for specific users:

[sharename]
   path = /share/path/username
   browsable = yes #optional
   read only = no
   force create mode = 0660 #forces permissions for created files
   force directory mode = 2770 #forces permissions for created folders
   valid users = username1, username2

Add system user (without home directory):
adduser --no-create-home --shell /usr/sbin/nologin --ingroup sambashare username

Add system user (with home directory):
sudo adduser --home /share/path/username --no-create-home --shell /usr/sbin/nologin --ingroup sambashare username

Add user to Samba DB & enable user:
smbpasswd -a username && smbpasswd -e username

Define directory owner:
chown username:sambashare /share/path/username

Change permissions(2=inherit group ownership):
chmod 2770 /share/path/username

Restart Samba service:
sudo service smbd restart

Configuration for Samba group:

[sharename]
   path = /share/path/all
   browsable = yes #optional
   read only = no
   force create mode = 0660
   force directory mode = 2770
   valid users = @sambashare #all Samba users

Define directory owner:
chown :sambashare /share/path/all

Change permissions:
chmod 2770 /share/path/all

Restart Samba service:
sudo service smbd restart

Mount Samba Share
#

Temporary mount Samba share

This should only be used for testing purposes, for best practice start the command with space, so that it does not show up in bash history:

mount -t cifs //IP/share /mount/path -o username=...,password=...

Mount Samba share with credential file

Create file for the user credentials:
vi /root/.sambacredentials

username=...
password=...

Change the file permissionsto owner read only:
chmod 400 /root/.sambacredentials

Test the mount:
mount -t cifs //IP/share /mount/path -o credentials=/root/.sambacredentials

Add entry to /etc/fstab:
//IP/share /mount/path cifs vers=3.0,credentials=/root/.sambacredentials

Samba Share Firewall Rules
# 

sudo ufw allow 137/udp &&
sudo ufw allow 138/udp &&
sudo ufw allow 139/tcp &&
sudo ufw allow 445/tcp