Add a disk to linux LVM command line

  • If your starting from scratch, ‘imaging’ or installing linux , insure you’ve partitioned with setup LVM on the first disk for this guide. As this is just the basic setup.

    Once you’ve reached the command line, you can run lsblk to list all block devices, noticing what is a partition and what is a device, where sda would be a device, and sda1 would be a partition:



    sda                    8:0    0 465.8G  0 disk 
    ├─sda1                 8:1    0   243M  0 part /boot
    ├─sda2                 8:2    0     1K  0 part 
    └─sda5                 8:5    0 465.5G  0 part 
      ├─bak10--vg-root   254:0    0 465.5G  0 lvm  /
      └─bak10--vg-swap_1 254:1    0     4G  0 lvm  [SWAP]
    sdb                    8:16   0 465.8G  0 disk

    Once you know the device you want to expand the LVM (Logical Volume Management) in this case ‘sdb’

    Take care to notice, there are many disk identifiers aka ‘sda’ depending on the specific distro you are using

    First you’ll want to install the required tools:

    sudo apt-get install system-config-lvm

    Then run:

    sudo vgdisplay

    In this case the LVM has already been expanded, either way, take note of the volume group, which you would have been prompted to define during the OS install.

    We can see here as the volume group as ‘VG Name’ bak10-vg


    --- Volume group ---
      VG Name               bak10-vg
      System ID             
      Format                lvm2
      Metadata Areas        2
      Metadata Sequence No  5
      VG Access             read/write
      VG Status             resizable
      MAX LV                0
      Cur LV                2
      Open LV               2
      Max PV                0
      Cur PV                2
      Act PV                2
      VG Size               931.28 GiB
      PE Size               4.00 MiB
      Total PE              238407
      Alloc PE / Size       238407 / 931.28 GiB
      Free  PE / Size       0 / 0   
      VG UUID               I3z4RM-RAsq-HfPD-FiUo-KxOZ-Jpsg-zROJPt

    We also need the logical volume root path, this can be found by running:

    sudo lvdisplay

    We can see the volume group root path is ‘LV Path /dev/bak10-vg/root’ Output:

    --- Logical volume ---
    LV Path                /dev/bak10-vg/root
    LV Name                root
    VG Name                bak10-vg
    LV UUID                ykeSJi-Q1mw-dWui-5D7p-Lr1y-wk18-swWVN8
    LV Write Access        read/write
    LV Creation host, time bak10, 2016-12-24 10:43:48 -0500
    LV Status              available
    # open                 1
    LV Size                927.28 GiB
    Current LE             237383
    Segments               2
    Allocation             inherit
    Read ahead sectors     auto
    - currently set to     256
    Block device           254:0
    --- Logical volume ---
    LV Path                /dev/bak10-vg/swap_1
    LV Name                swap_1
    VG Name                bak10-vg
    LV UUID                URTRk2-lcke-7oq6-TAtK-EGg8-qyTf-pAmr9Z
    LV Write Access        read/write
    LV Creation host, time bak10, 2016-12-24 10:43:48 -0500
    LV Status              available
    # open                 2
    LV Size                4.00 GiB
    Current LE             1024
    Segments               1
    Allocation             inherit
    Read ahead sectors     auto
    - currently set to     256
    Block device           254:1

    Now we convert the disk ‘sdb’ into a physical volume by running:

    sudo pvcreate /dev/sdb

    Then we add the physical volume to the volume group by extending the existing volume group to the second disk:

    sudo vgextend bak10-vg /dev/sdb

    Then we allocate the physical volume to the logical volume. You can allocate a specific partition or percentage of the new disk, however this is basic by adding the complete disk:

    sudo lvextend -l +100%FREE /dev/bak10-vg/root

    Now we must resize the volume group to the new physical drive:

    sudo resize2fs /dev/bak10-vg/root

    The LVM has been expanded to the second disk ‘/dev/sdb’, where the first disk contains a default and basic partitioning scheme :

    sda                    8:0    0 465.8G  0 disk 
    ├─sda1                 8:1    0   243M  0 part /boot
    ├─sda2                 8:2    0     1K  0 part 
    └─sda5                 8:5    0 465.5G  0 part 
      ├─bak10--vg-root   254:0    0 927.3G  0 lvm  /
      └─bak10--vg-swap_1 254:1    0     4G  0 lvm  [SWAP]
    sdb                    8:16   0 465.8G  0 disk 
    └─bak10--vg-root     254:0    0 927.3G  0 lvm  /

    None the less, we can see the two available physical disks ‘sda and sdb’ are now part of one file system.

    Where sda contains necessary basic partitions, and the second disk is now part of the volume group as usable space.

    Fin! Enjoy your new space!

Tmux Commands

screen and tmux

A comparison of the features (or more-so just a table of notes for accessing some of those features) for GNU screen and BSD-licensed tmux.

The formatting here is simple enough to understand (I would hope). ^ means ctrl+, so ^x is ctrl+x. M- means meta (generally left-alt or escape)+, so M-x is left-alt+x

It should be noted that this is no where near a full feature-set of either group. This - being a cheat-sheet - is just to point out the most very basic features to get you on the road.

Trust the developers and manpage writers more than me. This document is originally from 2009 when tmux was still new - since then both of these programs have had many updates and features added (not all of which have been dutifully noted here).

Action tmux screen
start a new session tmux OR
tmux new OR
tmux new-session
re-attach a detached session tmux attach OR
tmux attach-session
re-attach an attached session (detaching it from elsewhere) tmux attach -d OR
tmux attach-session -d
screen -dr
re-attach an attached session (keeping it attached elsewhere) tmux attach OR
tmux attach-session
screen -x
detach from currently attached session ^b d OR
^b :detach
^a ^d OR
^a :detach
rename-window to newname ^b , <newname> OR
^b :rename-window <newn>
^a A <newname>
list windows ^b w ^a w
list windows in chooseable menu ^a "
go to window # ^b # ^a #
go to last-active window ^b l ^a ^a
go to next window ^b n ^a n
go to previous window ^b p ^a p
see keybindings ^b ? ^a ?
list sessions ^b s OR
tmux ls OR
tmux list-sessions
screen -ls
toggle visual bell ^a ^g
create another window ^b c ^a c
exit current shell/window ^d ^d
split window/pane horizontally ^b " ^a S
split window/pane vertically ^b % ^a |
switch to other pane ^b o ^a <tab>
kill the current pane ^b x OR (logout/^D)
collapse the current pane/split (but leave processes running) ^a X
cycle location of panes ^b ^o
swap current pane with previous ^b {
swap current pane with next ^b }
show time ^b t
show numeric values of panes ^b q
toggle zoom-state of current pane (maximize/return current pane) ^b z
break the current pane out of its window (to form new window) ^b !
re-arrange current panels within same window (different layouts) ^b [space]
Kill the current window (and all panes within) ^b killw [target-window]
  • Again running smartctl after all is said and done:

    smartctl --all /dev/sda

    ddrescue-smartctl-after-rescue.png ddrescue-smartctl-2.png

    Yet an old drive in itself, I run the wheels off of them, and monitor regularly as anyone should.

    read more
  • Clone hard drive with ddrescue

    Testing a hard drive for failure via smartmontools

    Install smartmontools if not already present: (debian)

    apt-get install smartmontools

    Locate specific hard drives currently installed:


    In this case I choose device ‘sda’

    smartctl --all /dev/sda -q errorsonly

    Example of failing hard drive: smart-failure.png

    Preparing a used hard drive for cloning

    Clearing existing partitions from destination hard drive:

    In this case the destination drive is defined as sdc:

    I’ll use fdisk to clear all existing partitions:

    fdisk /dev/sdc Then print partition existing on sdc by typing the letter p



    The above image shows some detail on the destination drive, including on FreeBSD partition named /dev/sdc4

    Since there is only one partition on the destination drive, we simply need to type the letter d at the fdisk command prompt:



    If there are more existing partitions on the destination drive, we are presented with them, and numbers to go along, we select which partition via numbers what we delete (in this case everything)


    Once we’ve removed the partitions, we type the letter w to write the changes, (actually delete the partitions)

    I type the letter p once again to make sure no partitions are still on the disk and then the letter w to write the changes:


    Using ddrescue to clone the hard drive:

    !Insure your drive letters are correct!

    The command I use to simplify the procedure including reading the damaged drive and putting as little pressure on it as we can manage, while getting as much data as we can, are as follows:

    Insure existing, or damaged hard drive first, and destination hard drive second (In other terms input file first and output file second)

    ddrescue -f -n /dev/sda /dev/sdc /root/recovery.log


    -f, --force overwrite output device or partition

    -n, --no-split do not try to split or retry failed blocks

    We set a log file, which ddrescue can read later if for any reason the proceedure fails in the middle. Or also if we do not get as close to a 100% success rate when finished, the log file will set ddrescue to only attempt to get failed blocks on additional runs.


    In this case 100% of the data was recovered, and transferred to the new hard drive:


    I run lsblk once again to check partitions have been transferred: ddrescue-new-partitions.png

    I then restart the machine:

    shutdown -r now

    After a restart, the journal will be recovered as well as other routine scripts run. I remove other old, damaged hard drives during the restart just before the BIOS kicks up.

    Again after a restart I run :




    Note This local server is a test environment running ProxMox. Everything running as it should after the clone.

    read more