• check status
• mount
  • mount ios
  • mount smb
  • mount nfs
  • remount
  • disconnect the mount
• LVM
  • check current status
  • add new pv ( Physical Volume )
  • moving home with lvm
  • extend lv
  • remove LVM
  • example
• performance
  • check NFS performance
  • iostat
  • sar
  • hdparm
  • dd
• samba
  • setup
  • configure
  • firewall is necessary
  • enable services

check status

• $ lsblk
• $ ncdu
• $ pvs
• $ lvs
• $ vgs
• $ pvscan
• $ lvscan
• $ pvdisplay
• $ vgdisplay
• $ lvdisplay
• $ fdisk -l
• $ sfdisk -l -uM
• $ lshw -class disk
• $ hwinfo --block --short
• $ cat /proc/partitions
• $ sudo blkid

mount

mount ios

$ [[ -z $(findmnt /mnt/tmp) ]] || umount -f /mnt/tmp
$ mkdir /mnt/tmp
$ mount -t iso9660 -o loop /vol/builds/os/linux/RHEL-6.6-20140926.0-Server-x86_64-dvd1.iso  /mnt/tmp/

mount smb

[!NOTE] references:

• Mounting a Samba share
• 如何在 macOS 中停用 SMB 1 或 NetBIOS
• Performance issues with SMB 2 and 3 connections
• Linux系统运维: Samba 应用

macos

• via GUI :

  • Go -> Connect toServer -> smb://<ip.address>/secured

• via cmd

  • osascript

    $ /usr/bin/osascript -e "try" -e "mount volume \"smb://guest@${host}\"" -e "end try"
    

  • mount

    $ mkdir -p /Volumes/mount
    $ sudo mkdir -p $(whoami):staff /Volumes/mount
    
    # mount
    $ mount -t smbfs //user1:<password>@<ip.address>/secured /Volumes/mount
    
    # mount_smbfs
    $ mount_smbfs //user1@<ip.address>/secured /Volumes/mount
    Password for <ip.address>: <password>
    
    # umount
    $ umount /Volumes/mount
    

• check

  $ mount
  ...
  //user1@<ip.address>/secured on /Volumes/mount (smbfs, nodev, nosuid, mounted by user1)
  

linux

$ smbclient --user=user1 -L //<ip.address>

# or
$ smbclient //<ip.address>/secured -U user1

mount nfs

# example
nfs server: 1.2.3.4
sub-folder: /a/b
mount to local: /mnt/mynfs

$ sudo mkdir -p /mnt/mynfs
$ sudo mount -t nfs 1.2.3.4:/a/b /mnt/mynfs

# or force using nfsversion 4
$ sudo mount -t nfs -o nfsvers=4 1.2.3.4:/a/b /mnt/mynfs -vvv

• test if sub-folder exists in remote nfs server

  $ showmount -e 1.2.3.4 | grep '/a/b'
  

• environment setup

  # centos
  $ yum install nfs-utils nfs-utils-lib
  $ yum install portmap (not required with NFSv4)
  
  # for nfs4
  
  # ubuntu
  $ apt-get install nfs-utils nfs-utils-lib
  

check mount

$ cat /etc/mtab | grep /folder_name
/dev/sdb1 /folder_name ext4 rw,seclabel,relatime,stripe=64 0 0

Check if folder is a mounted remote filesystem

$ df -P -T /folder_name
Filesystem     Type 1024-blocks     Used  Available Capacity Mounted on
/dev/sdb1      ext4  744******* 658***** 699*******       1% /folder_name

• df

  $ df /local_storage
  Filesystem      1K-blocks     Used  Available Use% Mounted on
  /dev/sdb1      744******* 658***** 699*******   1% /folder_name
  

• /etc/fstab

  [!NOTE|label:references:]

  • iMarslo : character#column

  $ cat /etc/fstab
  $ sed 's/#.*//' /etc/fstab | column --table --table-columns SOURCE,TARGET,TYPE,OPTIONS,PASS,FREQ --table-right PASS,FREQ
  

• findmnt

  $ findmnt --fstab /local_storage
  TARGET         SOURCE    FSTYPE OPTIONS
  /local_storage /dev/sdb1 ext4   defaults
  

check nfs mount points

$ df -h -F nfs [ | column -t ]
$ mount | column -t | grep -E 'type.*nfs
$ findmnt /mnt/mynfs

check mount version

• local

  $ rpcinfo -p localhost
    program vers proto   port  service
     100000    4   tcp    111  portmapper
     100000    3   tcp    111  portmapper
     100000    2   tcp    111  portmapper
     100000    4   udp    111  portmapper
     100000    3   udp    111  portmapper
     100000    2   udp    111  portmapper
     100024    1   udp  38978  status
     100024    1   tcp  36415  status
     100021    1   udp  51669  nlockmgr
     100021    3   udp  51669  nlockmgr
     100021    4   udp  51669  nlockmgr
     100021    1   tcp  42699  nlockmgr
     100021    3   tcp  42699  nlockmgr
     100021    4   tcp  42699  nlockmgr
  

• remote

  $ rpcinfo 1.2.3.4 | egrep "service|nfs"
     program version netid     address          service    owner
      100003    3    udp       1.2.3.4.8.1      nfs
      100003    3    tcp       1.2.3.4.8.1      nfs
  

setup nfs mount by default server boot

$ sudo bash -c "cat > /etc/fstab" << EOF
1.2.3.4:/a/b    /mnt/mynfs nfs defaults 0 0
EOF

# i.e.:
$ cat /etc/fstab | grep -v '^#' | column -t
/dev/mapper/cl-root                             /               xfs   defaults                    0  0
UUID=18c35fe1-36ad-4d7e-aeb6-88bdb6b145af       /boot           ext4  defaults                    1  2
UUID=6C3A-C81A                                  /boot/efi       vfat  umask=0077,shortname=winnt  0  2
/dev/mapper/cl-home                             /home           xfs   defaults                    0  0
/dev/mapper/cl-swap                             swap            swap  defaults                    0  0
1.2.3.4:/a/b                                    /path/to/mount  nfs   defaults                    0  0

related configure

• /etc/fstab
• /etc/nsswitch.conf
• /etc/nfsmount.conf
• /etc/nfs.conf
• /proc/mounts

remount

$ sudo mount -oremount,rw /

# or
$ sudo mount -oremount,ro /

disconnect the mount

$ sudo umount /mnt/mynfs

• device is busy

  [!NOTE|label:references:]

  • umount: device is busy. Why?

  # check who is occupy the device
  $ fuser -vm /path/to/mount
  $ sudo fuser -vm /jenkins
                       USER        PID ACCESS COMMAND
  /path/to/mount:      root     kernel mount /path/to/mount
                       devops    1369210 ..c.. bash
                       marslo    1377303 ..c.. bash
  
  # or
  $ lsof +f -- /path/to/mount
  # or interactively kill only processes with files open for writing
  $ sudo fuser -vmMkiv /path/to/mount
  # or force kill directly without asking
  $ sudo fuser -vmMk /path/to/mount
  
  # logout
  $ sudo pkill -KILL -u marslo
  $ sudo pkill -KILL -u devops
  
  # umount again
  $ sudo umount -f /path/to/mount
  

LVM

[!NOTE|label:reference:]

• CONFIGURING AND MANAGING LOGICAL VOLUMES
• CHAPTER 5. MODIFYING THE SIZE OF A LOGICAL VOLUME
• LVM HOWTO
• * Logical Volume Manager Administration
• * LVM in Linux — Create and Extend a Logical Volume

COMMAND	NAME
vg	Volume Group
pv	Physical Volume
lv	Logical Volume

check current status

• lvm

  $ sudo vgs
    VG       #PV #LV #SN Attr   VSize    VFree
    vgubuntu   1   2   0 wz--n- <931.01g    0
  
  $ sudo lvs
    LV     VG       Attr          LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
    root   vgubuntu -wi-ao----    <929.10g
    swap_1 vgubuntu -wi-ao----    1.91g
  
  $ sudo pvs
    PV             VG       Fmt  Attr PSize    PFree
    /dev/nvme0n1p2 vgubuntu lvm2 a--  <931.01g      0
    /dev/sda3               lvm2 ---    <1.82t  <1.82t
  

• disk status

  $ sudo lsblk
  NAME                MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
  sda                   8:0    0   1.8T  0 disk
  ├─sda1                8:1    0   600M  0 part
  ├─sda2                8:2    0     1G  0 part /media/devops/99dad889-9bcc-4edb-baa9-3433c2502f18
  └─sda3                8:3    0   1.8T  0 part
  sdb                   8:16   1     0B  0 disk
  sr0                  11:0    1  1024M  0 rom
  nvme1n1             259:0    0 931.5G  0 disk
  ├─nvme1n1p1         259:2    0   512M  0 part
  └─nvme1n1p2         259:3    0   931G  0 part /media/devops/f99da1e7-9555-4cdc-9781-6dbc9e6153ca
  nvme0n1             259:1    0 931.5G  0 disk
  ├─nvme0n1p1         259:4    0   512M  0 part /boot/efi
  └─nvme0n1p2         259:5    0   931G  0 part
    ├─vgubuntu-root   253:0    0 929.1G  0 lvm  /var/snap/firefox/common/host-hunspell
    │                                           /
    └─vgubuntu-swap_1 253:1    0   1.9G  0 lvm  [SWAP]
  

add new pv ( Physical Volume )

$ sudo pvcreate /dev/nvme1n1p2
  Can't open /dev/nvme1n1p2 exclusively.  Mounted filesystem?
  Can't open /dev/nvme1n1p2 exclusively.  Mounted filesystem?

$ sudo mount | grep f99da1e7-9555-4cdc-9781-6dbc9e6153ca
/dev/nvme1n1p2 on /media/devops/f99da1e7-9555-4cdc-9781-6dbc9e6153ca type ext4 (rw,nosuid,nodev,relatime,errors=remount-ro,uhelper=udisks2)
$ sudo umount /dev/nvme1n1p2
$ sudo mount | grep f99da1e7-9555-4cdc-9781-6dbc9e6153ca

$ sudo lsblk /dev/nvme1n1
NAME                MAJ:MIN RM   SIZE RO TYPE MOUNTPOINTS
nvme1n1             259:0    0 931.5G  0 disk
├─nvme1n1p1         259:2    0   512M  0 part
└─nvme1n1p2         259:3    0   931G  0 part

$ sudo pvcreate /dev/nvme1n1p2
WARNING: ext4 signature detected on /dev/nvme1n1p2 at offset 1080. Wipe it? [y/n]: y
  Wiping ext4 signature on /dev/nvme1n1p2.
  Physical volume "/dev/nvme1n1p2" successfully created.

$ sudo pvs
  PV             VG       Fmt  Attr PSize    PFree
  /dev/nvme0n1p2 vgubuntu lvm2 a--  <931.01g      0
  /dev/nvme1n1p2          lvm2 ---   931.01g 931.01g
  /dev/sda3               lvm2 ---    <1.82t  <1.82t

moving home with lvm

[!NOTE|label:references]

• Moving /home with LVM

extend lv

# check status
$ sudo pvs
   PV         VG        Fmt  Attr PSize    PFree
    /dev/vda3  ubuntu-vg lvm2 a--   <38.00g     0
    /dev/vdb1  ubuntu-vg lvm2 a--  <275.00g     0
$ sudo vgs
    VG        #PV #LV #SN Attr   VSize    VFree
    ubuntu-vg   2   2   0 wz--n- <313.00g     0
$ sudo lvs
   LV             VG        Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
    ubuntu-lv      ubuntu-vg -wi-ao---- <100.00g
    ubuntu-lv-home ubuntu-vg -wi-ao----  100.00g
    ubuntu-lv-var  ubuntu-vg -wi-ao----  100.00g
$ sudo dmidecode -t1
$ sudo blkid
$ lsblk

# enable qemu-guest-agent
$ sudo apt-get install qemu-guest-agent
$ sudo systemctl restart qemu-guest-agent.service
$ sudo systemctl enable qemu-guest-agent.service
$ sudo systemctl status qemu-guest-agent.service

# create pv
$ sudo pvcreate /dev/temp

# extend vg
$ sudo vgextend ubuntu-vg /dev/temp

# extend lv
$ sudo lvextend -L +100G /dev/ubuntu-vg/ubuntu-lv-home
$ sudo resize2fs /dev/ubuntu-vg/ubuntu-lv-home

remove LVM

[!TIP]

• remove order:
  1. lv
  2. pv
  3. vg
• 15.2.2. Removing an LVM2 Logical Volume for Swap
• 5.3.10. Removing Volume Groups
• Linux Quick Tip: How to Delete or Remove LVM volumes
• Removing an existing LVM volume

$ sudo lvremove /dev/cl/home
# for swap
$ sudo swapoff -v /dev/cl/swap
$ sudo lvremove /dev/cl/swap
# and remove swap from `/etc/fstab`
$ sudo awk '!/\/dev\/cl\/swap/' /etc/fstab

$ sudo pvremove <pv-name>
$ sudo vgremove <vg-name>

example

• extends the logical volume /dev/myvg/homevol to 12 gigabytes

  $ sudo lvextend -L12G /dev/myvg/homevol
  lvextend -- extending logical volume "/dev/myvg/homevol" to 12 GB
  lvextend -- doing automatic backup of volume group "myvg"
  lvextend -- logical volume "/dev/myvg/homevol" successfully extended
  

• adds another gigabyte to the logical volume /dev/myvg/homevol

  $ sudo lvextend -L+1G /dev/myvg/homevol
  lvextend -- extending logical volume "/dev/myvg/homevol" to 13 GB
  lvextend -- doing automatic backup of volume group "myvg"
  lvextend -- logical volume "/dev/myvg/homevol" successfully extended
  

performance

check NFS performance

• nfsstat
• nfsiostat
• collectl
  • collectl -sjmf -oT
  • collectl -sn --verbose -oT
  • collectl -sJ -oTm
• tshark -R nfs -i eth0
• nfswatch
• netstat -plaute | grep nfs
• watch -d "netstat -plaute | grep nfs | sort -k 4,5"
• iostat -mx <delay in sec.> <devices>
• sudo fio --randrepeat=1 --ioengine=libaio --direct=0 --gtod_reduce=1 --name=test1 --filename=/media/ramdisk/test --bs=4k --iodepth=64 --size=4G --readwrite=randrw --rwmixread=75
• time dd if=/dev/zero of=/mnt/nfs/testfile bs=16k count=128k
• iozone -aRcU /mnt/nfs/ -f /mnt/nfs/testfile > logfile

iostat

$ iostat -x -d 1
Linux 3.10.0-957.27.2.el7.x86_64 (dc5-ssdfwtst3)  01/15/2021  _x86_64_  (4 CPU)

Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await r_await w_await  svctm  %util
sda               0.00     0.09    0.07   13.91     6.83    81.26    12.61     0.01    0.93   11.40    0.88   0.38   0.53
dm-0              0.00     0.00    0.07   14.00     6.83    81.26    12.53     0.01    0.95   11.60    0.90   0.38   0.53
dm-1              0.00     0.00    0.00    0.00     0.00     0.00    52.91     0.00    0.64    0.64    0.00   0.48   0.00

sar

$ sar -bdp 1
Linux 3.10.0-957.27.2.el7.x86_64 (dc5-ssdfwtst3)  01/15/2021  _x86_64_  (4 CPU)

05:44:20 AM       tps      rtps      wtps   bread/s   bwrtn/s
05:44:21 AM    863.00    863.00      0.00  47048.00      0.00

05:44:20 AM       DEV       tps  rd_sec/s  wr_sec/s  avgrq-sz  avgqu-sz     await     svctm     %util
05:44:21 AM       sda    863.00  47048.00      0.00     54.52      2.86      3.33      0.16     14.20
05:44:21 AM centos-root    863.00  47048.00      0.00     54.52      2.88      3.33      0.16     14.20
05:44:21 AM centos-swap      0.00      0.00      0.00      0.00      0.00      0.00      0.00      0.00

hdparm

[!NOTE] hdparm - get/set SATA/IDE device parameters

references:

• Linux and Unix Test Disk I/O Performance With dd Command
• hdparm Command Examples in Linux
• hdparm command in Linux with Examples

$ sudo hdparm -Tt /dev/sda3
/dev/sda3:
 Timing cached reads:   15900 MB in  1.99 seconds = 7978.64 MB/sec
 Timing buffered disk reads: 1796 MB in  3.00 seconds = 598.17 MB/sec

$ sudo hdparm -Tt /dev/sda3
/dev/sda3:
 Timing cached reads:   18924 MB in  1.98 seconds = 9539.84 MB/sec
 Timing buffered disk reads: 102 MB in 12.88 seconds =   7.92 MB/sec

dd

[!NOTE] references:

• Linux and Unix Test Disk I/O Performance With dd Command

$ flush
$ echo 3 | sudo tee /proc/sys/vm/drop_caches
$ time dd if=/path/to/bigfile of=/dev/null bs=8k

• write speed

  $ dd if=/dev/zero of=/tmp/test1.img bs=1G count=1 oflag=dsync
  

• server latency time

  $ dd if=/dev/zero of=/tmp/test2.img bs=512 count=1000 oflag=dsync
  

samba

[!NOTE] references:

• Instructions for setting up a secure Samba share on CentOS 8 Linux
• How to Install and Configure Samba on CentOS 8

setup

# install
$ sudo dnf install samba samba-common samba-client
$ sudo mv /etc/samba/smb.conf /etc/samba/smb.con.bak

# setup user
$ sudo groupadd secure_group
$ sudo useradd -g secure_group user1
$ sudo useradd -g secure_group user2

# create folder
$ sudo mkdir -p /srv/samba/shared
$ sudo mkdir -p /srv/samba/secure_shared

$ sudo smbpasswd -a user1
  password_1
$ sudo smbpasswd -a user2
  password_2

configure

$ cat /etc/samba/smb.conf
[global]
workgroup = WORKGROUP
server string = Samba Server %v
netbios name = centos-8
security = user
map to guest = bad user
dns proxy = no
ntlm auth = yes              // for windows

• for anonymous

  $ sudo chmod -R 0755 /srv/samba/shared
  $ sudo chown -R nobody:nobody /srv/samba/shared
  $ sudo chcon -t samba_share_t /srv/samba/shared
  # or
  $ sudo chcon -R system_u:object_r:samba_share_t:s0 /srv/samba/shared
  
  $ cat /etc/samba/smb.conf
  [anonymous]
  path = /srv/samba/shared
  browsable =yes
  writable = yes
  guest ok = yes
  read only = no
  force user = nobody
  
  $ testparm
  

• for secured

  $ sudo chmod -R 0770 /srv/samba/secure_shared
  $ sudo chcon -t samba_share -p /srv/samba/secure_shared
  $ sudo chown -R root:secure_group /srv/samba/secure_shared
  
  $ cat /etc/samba/smb.conf
  [secured]
  path = /srv/samba/secure_shared
  valid users = @secure_group
  guest ok = no
  writable = yes
  browsable = yes
  
  # verify the configuration is sound
  $ testparm
  

firewall is necessary

# centos
$ sudo firewall-cmd --add-service=samba --zone=public --permanent
$ sudo firewall-cmd --reload

# ubuntu: https://help.ubuntu.com/lts/serverguide/firewall.html
$ sudo ufw app list
$ sudo ufw allow Samba
$ sudo ufw allow from 192.168.0.0/24 to any app Samba
$ sudo ufw app info Samba

enable services

# enable service
$ sudo systemctl start smb
$ sudo systemctl enable smb
$ sudo systemctl status smb
$ sudo systemctl start nmb
$ sudo systemctl enable nmb
$ sudo systemctl status nmb

• config

  [!TIP] FILES :

  • /etc/nsmb.conf
    • The global configuration file.
  • ~/Library/Preferences/nsmb.conf
    • The user's configuration file, conflicts will be overwritten by the global file.

  $ cat /etc/nsmb.conf
  [default]
  signing_required=no
  file_ids_off=yes