Engineering-Tech Wiki

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== VM disk Expansion LVM with XFS/EXT4 =======

Expand the original disk or add a second vdisk from **Infrastructure Client**.\\

If you are on a kernel newer or equal to 2.6.32 then you can issue the command

<code>echo "1" > /sys/block/sdX/device/rescan</code>

to get the new size w/o reboot.


In case you cant see the "disk" do this:

  echo "- - -" > /sys/class/scsi_host/host0/scan
  
Do this for all host0,1,2 etc.


or

  echo "1" > /sys/class/scsi_device/2\:0\:0\:0/device/rescan

whereby after scsi_device you need to find the correct scsi device

or

  apt-get install scsitools
  rescan-scsi-bus

At the end it should list that a new device was found, note down the name/number!

  echo '1' > /sys/class/scsi_disk/32\:0\:1\:0/device/rescan

IMPORTANT: Be sure to replace the 32\:0\:1\:0 with the appropriate disk for your purposes. 


**EXPAND ORIGINAL DISK**

Create an additional partition on the free space, say you increased the existing disc

from 8GB to 15GB. The partition type is 8e.

  cfdisk /dev/sda or cfdisk /dev/sdb


**RESIZE ORIGINAL DISK**

Resize the already existing partition, e.g. /dev/sda4 to the newly created free partition.

  cfdisk /dev/sda or cfdisk /dev/sdb

Now resize the Physical Volume to the new size

  pvresize /dev/sda4

extend the logical volume

  lvextend -l +100%FREE  /dev/data-www-vg/lvol-datawww

next resize the file system

  resize2fs -p /dev/data-www-vg/lvol-datawww


If you get a error:

<color #ed1c24>GPT PMBR size mismatch (2362232011 != 2516582399) will be corrected by w(rite).</color>

run this command:

  parted -l

and when asked to Fix/Cancel? type **F**

# for example if the new partition is /dev/sda3

# create logical disk /dev/sda3 of type 8e (Linux LVM)

# make disk visible to linux

  partprobe
  pvcreate /dev/sda3

now you have to extend the volgroup. use ''lvdisplay'' to see which is the name of the group,\\
in this example it's **base**

  lvdisplay

<code>
  --- Logical volume ---
  LV Name                /dev/base/root
  VG Name                base
  LV UUID                8cL9Qd-ksIn-1Ve2-94ym-gTrW-8jet-91tnah
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                5.00 GB
  Current LE             1280
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:0
   
  --- Logical volume ---
  LV Name                /dev/base/tmp
  VG Name                base
  LV UUID                mEnEXY-UtOf-P439-MDpg-BlT3-n8hI-Q6KIfm
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.00 GB
  Current LE             256
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:1
   
  --- Logical volume ---
  LV Name                /dev/base/swap
  VG Name                base
  LV UUID                fm2A23-FPb3-itQa-Fvf2-QQmj-giwI-j8FZAf
  LV Write Access        read/write
  LV Status              available
  # open                 2
  LV Size                2.00 GB
  Current LE             512
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:2
   
  --- Logical volume ---
  LV Name                /dev/base/data
  VG Name                base
  LV UUID                GZKUbb-hZn2-igXN-3dxj-TNz9-1C15-I8u8MR
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.52 GB
  Current LE             389
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           254:3
</code>

and we assume the new partition is /dev/sda3

  vgextend base /dev/sda3

check with ''pvscan'' if the extend was successfull

  pvscan

Now we extend the "data" partition to 11.5 GB. See man lvextend for other options\\
11.5 G is the NEW total size of the disk we want to extend!

Extend the LV to use all free space
  lvextend -l +100%FREE /dev/base/data

Extend with 20G
  lvextend -L +20G  /dev/base/data 

now we have to grow the filesystem /data

   xfs_growfs /data


===== FOR EXT3/4 =====

Extend filesystem  to use all free space

  vgextend base /dev/sda3

  lvextend -l +100%FREE /dev/base/root

Check that the filesystem is ok, **but only if the FS is unmounted**

  fsck.ext4 -f /dev/base

Now resize the filesystem

Debian System:

  resize2fs -p /dev/base/root

Centos/Fedora System:

  resize4fs -p /dev/base/root

===== For swap =====

  swapoff /dev/base/swap
  lvextend -L 3.9G /dev/base/swap
  mkswap /dev/base/swap
  swapon /dev/base/swap
  free

Check if filesystems are ok, and only then release the snapshot

Fix issue with swap

  * swapoff: /dev/dm-1: swapoff failed: Cannot allocate memory

[[https://unix.stackexchange.com/questions/321675/unable-to-swapoff-but-enough-physical-memory-is-available/472012|Swapoff Cannot Allocate Memory]]

<del>[[https://leizhilong.github.io/blog/2018-11-12-case-study-swapoff-cannot-allocate-memory/|Swapoff Cannot Allocate Memory]]</del>


======= Create LVM =======

Find all LVM VG

  vgscan

Create Physical Volumes

Der Befehl pvcreate legt den VGDA Block auf dem PV an. Er muss für jedes PV ausgeführt werden, bevor es von LVM verwendet werden kann:

   pvcreate /dev/hda3

Volume Groups anlegen

Jetzt legen wir mit 'vgcreate <VolumeGroup> <Partition(en)>' unsere Volume Group an und nennen sie "vg01":

   vgcreate vg01 /dev/hda3 /dev/hdb2

Logische Volumes anlegen.

Hier legen wir jetzt alle unsere logischen Volumes an. Als Namen verwenden wir, etwas fantasielos, lvol1, lvol2 und lvol3. Dabei bedienen wir uns mit dem Plattenplatz auf Volume Group vg01, der einzigen Volume Group in diesem Beispiel. Es ist offensichtlich, dass wir hier nicht mehr Plattenplatz "verteilen" können, als wir bei vgcreate in die Volume Group "hineingesteckt" haben, und zwar in Form der beiden Partitionen hda3 und hdb2. (lvcreate -L<Grösse> -n <LogicalVolumeName> <Volume Group>).

   lvcreate -l +100%FREE -n lvol1 vg01

oder wir könne die Größen angeben! (1500M)

   lvcreate -L 1500M -n lvol1 vg01

Filesysteme anlegen

Ab jetzt können die logischen Partitionen, genau so wie gewöhnliche Partitionen, über Ihre Device Files angesprochen werden. Gewöhliche Partitionen werden mit /dev/sd[a-z]* oder /dev/hd[a-z]* bezeichnet; Logische Volumes werden mit /dev/VolumeGroupName/LogicalVolumeName angesprochen. Mit mke2fs <LogicalVolumeName> legen wir die ext2 Filesysteme an:

  mkfs.ext4 /dev/vg01/lvol1

fstab anpassen

Damit die neuen Filesysteme nun bei jedem Systemstart automatisch gemountet werden, müssen wir sie in die Datei /etc/fstab eintragen (siehe 'man fstab'). In unserem Scenario sehen die zusätzlichen Einträge wie folgt aus:

   /dev/vg01/lvol1 /usr ext4 defaults 1 2

===== Links =====


[[http://www.thegeekstuff.com/2010/08/how-to-create-lvm/|How To Create LVM Using vgcreate, lvcreate, and lvextend lvm2 Commands]]\\
[[https://unix.stackexchange.com/questions/47380/where-does-lvm-store-data|Where does LVM store data?]]\\
[[http://www.howtoforge.com/linux_lvm|A Beginner's Guide To LVM]]\\
[[http://wiki.gentoo.org/wiki/LVM#LV_.28Logical_Volume.29|LVM]] VERY GOOD SOURCE!\\
[[http://www.funtoo.org/LVM_Fun#Physical_volumes_creation|LVM Fun]] VERY GOOD SOURCE!\\
[[http://serverfault.com/questions/223361/how-to-recover-logical-volume-deleted-with-lvremove|How to recover logical volume deleted with lvremove]]\\
[[http://www.novell.com/support/kb/doc.php?id=3803380|LVM Volume Group Shows "unknown device"]]

[[https://www.tutorialspoint.com/unix_commands/pvresize.htm|pvresize - Unix, Linux Command]]

http://www.linuxhaven.de/dlhp/HOWTO-test/DE-LVM-HOWTO-2.html\\
http://www.howtogeek.com/howto/40702/how-to-manage-and-use-lvm-logical-volume-management-in-ubuntu/