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Showing posts with label LVM. Show all posts
Showing posts with label LVM. Show all posts

Monday, September 3, 2018

How to reduce (lvreduce) the Logical Volume in Linux Server

Monday, September 03, 2018 0
How to reduce (lvreduce) the Logical Volume in Linux Server.

 Situation

 Here, /app1 is 100GB filesystem. We need to reduce it to 70GB 

 [root@testserver ~]# df -hP
Filesystem                                                 Size  Used Avail Use% Mounted on
/dev/mapper/vg_main-lv_root                   31G  2.0G    28G   7%    /
tmpfs                                                        3.7G     0      3.7G   0%   /dev/shm
/dev/xvdb1                                              477M   93M  355M  21%  /boot
/dev/mapper/vg_DPFERT-lv_app1           99G   11G    84G  11%   /app1
[root@testserver ~]# vgs
  VG                #PV #LV #SN Attr      VSize    VFree
  vg_DPFERT    1   1      0    wz--n-  100.00g    0
  vg_main           1   2      0    wz--n-    31.50g   0

 [root@testserver ~]# fdisk -l /dev/xvdc

 Disk /dev/xvdc: 107.4 GB, 107374182400 bytes
255 heads, 63 sectors/track, 13054 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

     Device Boot      Start         End      Blocks   Id  System
/dev/xvdc1               1       13054   104856254+  8e  Linux LVM

 STEP 1 : First Unmount the LV

 STEP 2 : Run e2fsck command to check the file system

 [root@testserver ~]# e2fsck -f /dev/vg_DPFERT/lv_app1
e2fsck 1.43-WIP (20-Jun-2013)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg_DPFERT/lv_app1: 57971/6553600 files (0.2% non-contiguous), 3073907/26213376 blocks
STEP 3 : Run resize2fs command for resizing the file system.

 [root@testserver ~]# resize2fs /dev/vg_DPFERT/lv_app1 70G 
resize2fs 1.43-WIP (20-Jun-2013)
Resizing the filesystem on /dev/vg_DPFERT/lv_app1 to 18350080 (4k) blocks.
The filesystem on /dev/vg_DPFERT/lv_app1 is now 18350080 blocks long.

 STEP 4 : Run lvreduce command to resuce the lvsize.

 [root@testserver ~]# lvreduce -L 70G /dev/vg_DPFERT/lv_app1
  WARNING: Reducing active logical volume to 70.00 GiB
  THIS MAY DESTROY YOUR DATA (filesystem etc.)
Do you really want to reduce lv_app1? [y/n]: y
  Size of logical volume vg_DPFERT/lv_app1 changed from 100.00 GiB (25599 extents) to 70.00 GiB (17920 extents).
  Logical volume lv_app1 successfully resized
[root@testserver ~]#

 STEP 5 : Mount the LV
[root@testserver ~]# lvs
  LV          VG                  Attr          LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv_app1  vg_DPFERT  -wi-a-----  70.00g
  lv_root    vg_main       -wi-ao----  31.22g
  lv_swap  vg_main       -wi-ao---- 288.00m

 [root@testserver ~]# vgs
  VG                  #PV #LV #SN Attr       VSize      VFree
  vg_DPFERT    1      1      0    wz--n-  100.00g   30.00g
  vg_main           1      2     0     wz--n-  31.50g     0
  
[root@testserver home]# df -hP
Filesystem                                          Size  Used Avail Use% Mounted on
/dev/mapper/vg_main-lv_root             31G   2.0G   28G   7%   /
tmpfs                                                  3.7G     0      3.7G   0%  /dev/shm
/dev/xvdb1                                        477M   93M  355M  21% /boot
/dev/mapper/vg_DPFERT-lv_app1     69G   11G   56G   16%  /app1

Hope it helps.
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Sunday, January 7, 2018

How to modify the Default Physical extent size of Physical Volume?

Sunday, January 07, 2018 0

There are 2 situation for modifying or Setting the Default Physical extent size in LVM.

1. Create a volume group with new Physical extent size. This method will be used before creating logical volume on that Volume Group.

 #vgcreate -s PE_SIZE 

 Here,
-s  --physicalextentsize Size[m|UNIT] - Sets the physical extent size of PVs in the VG.  The value must be either a power of 2 of at least 1 sector (where the sector size is the largest sector size of the PVs currently used in the VG), or at least 128KiB.  Once this value has been set, it is difficult to change without recreating the VG,unless no extents need moving.

2. Modify the Existing value of Physical extent size.

 - remove all Logical Volumes of the Volume Group with lvremove
- do a vgreduce on that VG.
- "vgchage -an" on that VG
- vgremove that VG
- setup the VG with large PE size (vgcreate -s PE_SIZE)

 A more "Forceful" approach is:
- "vgchange -a n" on the VG
- "pvcreate -ff" on all its PVs
- setup the VG with large PE size (vgcreate -s PE_SIZE)
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Saturday, January 6, 2018

Display what extents are allocated on the physical volume to logical volume

Saturday, January 06, 2018 0
We can see what extents are allocated on the physical volume

 NAME
       pvdisplay - Display various attributes of physical volume(s)
   
pvdisplay shows the attributes of PVs, like size, physical extent size, space used for the VG descriptor area, etc. Here pvdisplay along with options --maps will show the what extents are allocated on the physical volume to the lv.

 [root@nsk postfix]# pvdisplay --maps /dev/sda2
  --- Physical volume ---
  PV Name                /dev/sda2
  VG Name                centos
  PV Size                  <19.00 GiB / not usable 3.00 MiB
  Allocatable              yes (but full)
  PE Size                   4.00 MiB
  Total PE                   4863
  Free PE                   0
  Allocated PE           4863
  PV UUID                 DQjmHN-fso4-Mu4t-3l1V-Yogj-ksTH-ROFiK7

   --- Physical Segments ---
  Physical extent 0 to 511:
    Logical volume      /dev/centos/swap
    Logical extents      0 to 511
  Physical extent 512 to 4862:
    Logical volume      /dev/centos/root
    Logical extents      0 to 4350

 Here,
         -m  --maps  Display the mapping of physical extents to LVs and logical extents.
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Sunday, December 17, 2017

Understanding the LVM Configuration Files in Linux

Sunday, December 17, 2017 0

Understanding the LVM Configuration Files in Linux

The following files are part of LVM configuration:

 /etc/lvm/lvm.conf
    Central configuration file read by the tools.

 etc/lvm/lvm_hosttag.conf
    For each host tag, an extra configuration file is read if it exists: lvm_hosttag.conf. If that file defines new tags,
    then further configuration files will be appended to the list of tiles to read in.
In addition to the LVM configuration files, a system running LVM includes the following files that affect LVM system setup:

 /etc/lvm/cache
    Device name filter cache file (configurable).

 /etc/lvm/backup/
    Directory for automatic volume group metadata backups (configurable).

 /etc/lvm/archive/
    Directory for automatic volume group metadata archives (configurable with regard to directory path and archive history depth).

 /var/lock/lvm/
    In single-host configuration, lock files to prevent parallel tool runs from corrupting the metadata; in a cluster, cluster-wide DLM is used.
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Wednesday, November 1, 2017

How to Add and Remove Object Tags in Logical Volume Manager (Linux Server)?

Wednesday, November 01, 2017 0

Add or Delete tags, below steps will be used.

To add or delete tags from physical volumes, use the --addtag or --deltag option of the
 pvchange command.                                                                          
To add or delete tags from volume groups, use the --addtag or --deltag option of the 
vgchange or vgcreate commands.
To add or delete tags from logical volumes, use the --addtag or --deltag option of the 
lvchange or lvcreate commands.    

As of the Red Hat Enterprise Linux 6.1 release, you can specify multiple --addtag and --deltag arguments within asingle pvchange, vgchange, or lvchange command. For example, the following command deletes the tags T9 and T10 and adds the tags T13 and T14 to the volume group VGTEST

vgchange --deltag T9 --deltag T10 --addtag T13 --addtag T14 VGTEST

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