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Removing VGs or LVs from LVM

While are many excellent tutorials about creating and using LVM on Linux, not may show you how you can remove disks from LVM Volume Groups (VG) and reclaim storage or how to remove a Logical Volume (LV) from your LVM set-up.

Here is what I did:
Use -t to TEST ANY LVM action first!
We are going to release 1 TB from LVM. The Volume group was extended with 1 TB storage to serve as a cheap NFS/CIFS file server when setting up our data center. It is now deprecated and replaced by a NAS so it's no longer needed.

1) check LVM; note the four 256 GB LUNs 

[root@server ~]# pvscan -v
    Wiping cache of LVM-capable devices
    Wiping internal VG cache
    Walking through all physical volumes
  PV /dev/sdb1   VG vgdata   lvm2 [50.00 GB / 0    free]
  PV /dev/sdc1   VG vgdata   lvm2 [256.00 GB / 0    free]
  PV /dev/sdd1   VG vgdata   lvm2 [256.00 GB / 0    free]
  PV /dev/sde1   VG vgdata   lvm2 [256.00 GB / 0    free]
  PV /dev/sdf1   VG vgdata   lvm2 [256.00 GB / 0    free]
  PV /dev/sdg    VG vgdata   lvm2 [10.00 GB / 5.00 GB free]
  PV /dev/sda3   VG system   lvm2 [7.88 GB / 0    free]
  Total: 7 [1.07 TB] / in use: 7 [1.07 TB] / in no VG: 0 [0   ]
[root@server ~]# vgscan -v
    Wiping cache of LVM-capable devices
    Wiping internal VG cache
  Reading all physical volumes.  This may take a while...
    Finding all volume groups
    Finding volume group "vgdata"
  Found volume group "vgdata" using metadata type lvm2
    Finding volume group "system"
  Found volume group "system" using metadata type lvm2
[root@server ~]# lvscan -v
    Finding all logical volumes
  ACTIVE            '/dev/vgdata/lvuln' [54.99 GB] inherit
  ACTIVE            '/dev/vgdata/lvshare' [1.00 TB] inherit
  ACTIVE            '/dev/system/root' [4.03 GB] inherit
  ACTIVE            '/dev/system/tmp' [1.84 GB] inherit
  ACTIVE            '/dev/system/var' [2.00 GB] inherit
[root@server ~]#


From the lvscan, we see that one separate Logical Volume (LV) lvshare was added to the VG vgdata and it holds the entire 1 TB.

2) check the Volume Group 

[root@server ~]# vgdisplay /dev/vgdata
  --- Volume group ---
  VG Name               vgdata
  System ID
  Format                lvm2
  Metadata Areas        6
  Metadata Sequence No  10
  VG Access             read/write
  VG Status             resizable
  MAX LV                256
  Cur LV                2
  Open LV               1
  Max PV                256
  Cur PV                6
  Act PV                6
  VG Size               1.06 TB
  PE Size               2.00 MB
  Total PE              555002
  Alloc PE / Size       552443 / 1.05 TB
  Free  PE / Size       2559 / 5.00 GB
  VG UUID               30mFGo-gcFZ-Dmx2-atLC-Wh44-qGL4-MCfwia


The LVM is healthy; Note that vgdata is resizable, currently has 6 PVs associated with it, all of them in use; extends are 2 MB each and there are 550000 of them: that's 1 TB; currently 5 GB capacity is free

Since vgdata contains 2 separate LVs, we can remove the LV lvshare.

[root@server ~]# lvremove -t -v /dev/vgdata/lvshare
  Test mode: Metadata will NOT be updated.
    Using logical volume(s) on command line
Do you really want to remove active logical volume "lvshare"? [y/n]: y
    Test mode: Skipping archiving of volume group.
    Found volume group "vgdata"
    Found volume group "vgdata"
    Releasing logical volume "lvshare"
    Test mode: Skipping volume group backup.
  Logical volume "lvshare" successfully removed
    Test mode: Wiping internal cache
    Wiping internal VG cache
[root@server ~]# lvremove -v /dev/vgdata/lvshare
    Using logical volume(s) on command line
Do you really want to remove active logical volume "lvshare"? [y/n]: y
    Archiving volume group "vgdata" metadata (seqno 10).
    Found volume group "vgdata"
    Removing vgdata-lvshare (253:4)
    Found volume group "vgdata"
    Releasing logical volume "lvshare"
    Creating volume group backup "/etc/lvm/backup/vgdata" (seqno 11).
  Logical volume "lvshare" successfully removed
[root@server ~]#

We've now deallocated the LV lvshare from the VG vgdata.
We still need to disassociate the 4 LUNs (PVs) from the VG:

[root@server ~]# vgdisplay -v /dev/vgdata
    Using volume group(s) on command line
    Finding volume group "vgdata"
  --- Volume group ---
  VG Name               vgdata
  System ID
  Format                lvm2
  Metadata Areas        6
  Metadata Sequence No  11
  VG Access             read/write
  VG Status             resizable
  MAX LV                256
  Cur LV                1
  Open LV               1
  Max PV                256
  Cur PV                6
  Act PV                6
  VG Size               1.06 TB
  PE Size               2.00 MB
  Total PE              555002
  Alloc PE / Size       28155 / 54.99 GB
  Free  PE / Size       526847 / 1.00 TB
  VG UUID               30mFGo-gcFZ-Dmx2-atLC-Wh44-qGL4-MCfwia

  --- Logical volume ---
  LV Name                /dev/vgdata/lvuln
  VG Name                vgdata
  LV UUID                xrPs1G-nKkd-0Mxp-JOfB-QYIk-zJKz-MwI2V5
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                54.99 GB
  Current LE             28155
  Segments               3
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:3

  --- Physical volumes ---
  PV Name               /dev/sdb1
  PV UUID               HkcRpz-mDRN-3SBC-Dtq3-f2tj-x8QA-J7slPT
  PV Status             allocatable
  Total PE / Free PE    25599 / 4

  PV Name               /dev/sdc1
  PV UUID               WMYlf1-0LPe-yasi-jdeC-GVKl-hTeI-ttZzoC
  PV Status             allocatable
  Total PE / Free PE    131071 / 131071

  PV Name               /dev/sdd1
  PV UUID               MsoDqY-uflF-Rw30-JEMK-tZ8k-VmB2-F2wBfK
  PV Status             allocatable
  Total PE / Free PE    131071 / 131071

  PV Name               /dev/sde1
  PV UUID               e0c037-vSBy-ATdS-9Cd3-2X2p-yroz-2dBOD3
  PV Status             allocatable
  Total PE / Free PE    131071 / 131071

  PV Name               /dev/sdf1
  PV UUID               ntIMPv-A8Vs-p7wk-KbP3-IsKk-1oMS-BJvZp5
  PV Status             allocatable
  Total PE / Free PE    131071 / 131071

  PV Name               /dev/sdg
  PV UUID               v1mkgm-OvIW-RvS1-6Vnf-yvll-BSL1-wm3ZDw
  PV Status             allocatable
  Total PE / Free PE    5119 / 2559

[root@server ~]# vgreduce -t -v /dev/vgdata /dev/sdc1
  Test mode: Metadata will NOT be updated.
    Finding volume group "vgdata"
    Using physical volume(s) on command line
    Test mode: Skipping archiving of volume group.
    Removing "/dev/sdc1" from volume group "vgdata"
    Test mode: Skipping volume group backup.
  Removed "/dev/sdc1" from volume group "vgdata"
    Test mode: Wiping internal cache
    Wiping internal VG cache
[root@server ~]# vgreduce -a -t -v /dev/vgdata
  Test mode: Metadata will NOT be updated.
    Finding volume group "vgdata"
    Using all physical volume(s) in volume group
  Physical volume "/dev/sdb1" still in use
    Test mode: Skipping archiving of volume group.
    Removing "/dev/sdc1" from volume group "vgdata"
    Test mode: Skipping volume group backup.
  Removed "/dev/sdc1" from volume group "vgdata"
    Test mode: Skipping archiving of volume group.
    Removing "/dev/sdd1" from volume group "vgdata"
    Test mode: Skipping volume group backup.
  Removed "/dev/sdd1" from volume group "vgdata"
    Test mode: Skipping archiving of volume group.
    Removing "/dev/sde1" from volume group "vgdata"
    Test mode: Skipping volume group backup.
  Removed "/dev/sde1" from volume group "vgdata"
    Test mode: Skipping archiving of volume group.
    Removing "/dev/sdf1" from volume group "vgdata"
    Test mode: Skipping volume group backup.
  Removed "/dev/sdf1" from volume group "vgdata"
  Physical volume "/dev/sdg" still in use
    Test mode: Wiping internal cache
    Wiping internal VG cache

Now for the real thing: we remove all unused PV from VG vgdata. Note how both sdb and sdg, both still in use by the LV lvuln, are skipped! 

[root@server ~]# vgreduce -a -v /dev/vgdata
    Finding volume group "vgdata"
    Using all physical volume(s) in volume group
  Physical volume "/dev/sdb1" still in use
    Archiving volume group "vgdata" metadata (seqno 11).
    Removing "/dev/sdc1" from volume group "vgdata"
    Creating volume group backup "/etc/lvm/backup/vgdata" (seqno 12).
  Removed "/dev/sdc1" from volume group "vgdata"
    Archiving volume group "vgdata" metadata (seqno 12).
    Removing "/dev/sdd1" from volume group "vgdata"
    Wiping cache of LVM-capable devices
    Creating volume group backup "/etc/lvm/backup/vgdata" (seqno 13).
  Removed "/dev/sdd1" from volume group "vgdata"
    Archiving volume group "vgdata" metadata (seqno 13).
    Removing "/dev/sde1" from volume group "vgdata"
    Wiping cache of LVM-capable devices
    Creating volume group backup "/etc/lvm/backup/vgdata" (seqno 14).
  Removed "/dev/sde1" from volume group "vgdata"
    Archiving volume group "vgdata" metadata (seqno 14).
    Removing "/dev/sdf1" from volume group "vgdata"
    Wiping cache of LVM-capable devices
    Creating volume group backup "/etc/lvm/backup/vgdata" (seqno 15).
  Removed "/dev/sdf1" from volume group "vgdata"
  Physical volume "/dev/sdg" still in use
[root@server ~]#

Check our status: 

[root@server ~]# vgdisplay -v /dev/vgdata
    Using volume group(s) on command line
    Finding volume group "vgdata"
  --- Volume group ---
  VG Name               vgdata
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  15
  VG Access             read/write
  VG Status             resizable
  MAX LV                256
  Cur LV                1
  Open LV               1
  Max PV                256
  Cur PV                2
  Act PV                2
  VG Size               60.00 GB
  PE Size               2.00 MB
  Total PE              30718
  Alloc PE / Size       28155 / 54.99 GB
  Free  PE / Size       2563 / 5.01 GB
  VG UUID               30mFGo-gcFZ-Dmx2-atLC-Wh44-qGL4-MCfwia

  --- Logical volume ---
  LV Name                /dev/vgdata/lvuln
  VG Name                vgdata
  LV UUID                xrPs1G-nKkd-0Mxp-JOfB-QYIk-zJKz-MwI2V5
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                54.99 GB
  Current LE             28155
  Segments               3
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:3

  --- Physical volumes ---
  PV Name               /dev/sdb1
  PV UUID               HkcRpz-mDRN-3SBC-Dtq3-f2tj-x8QA-J7slPT
  PV Status             allocatable
  Total PE / Free PE    25599 / 4

  PV Name               /dev/sdg
  PV UUID               v1mkgm-OvIW-RvS1-6Vnf-yvll-BSL1-wm3ZDw
  PV Status             allocatable
  Total PE / Free PE    5119 / 2559

[root@server ~]#

Note the new status of the Volume Group (VG):

  • resizable

  • only 2 PVs, both in use

  • 60 GB capacity, 5 GB free

  • a few extends left on sdb1 and 2500 on sdg. Since extends are 2 MB, that's 5 GB

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