LVM : Configure Mirroring Volume2022/07/07

	Configure Mirroring Volumes. It is like RAID 1.
[1]	For example, create a Mirroring Volume with Physical Volume [/dev/sdb1] and [/dev/sdc1].

# create volume group [vg_mirror] with [/dev/sdb1] and [/dev/sdc1]

[root@dlp ~]#

vgcreate vg_mirror /dev/sdb1 /dev/sdc1

  Volume group "vg_mirror" successfully created

# create a mirroring volume

[root@dlp ~]#

lvcreate -L 50G -m1 -n lv_mirror vg_mirror

[ 2063.377949] raid6: skip pq benchmark and using algorithm avx2x4
[ 2063.379250] raid6: using avx2x2 recovery algorithm
[ 2063.382543] async_tx: api initialized (async)
[ 2063.404995] device-mapper: raid: Loading target version 1.15.1
[ 2063.479381] device-mapper: raid: Superblocks created for new raid set
[ 2063.490722] md/raid1:mdX: not clean -- starting background reconstruction
[ 2063.492076] md/raid1:mdX: active with 2 out of 2 mirrors
[ 2063.817349] mdX: bitmap file is out of date, doing full recovery
[ 2063.849297] md: resync of RAID array mdX
  Logical volume "lv_mirror" created.

[root@dlp ~]#

lvdisplay /dev/vg_mirror/lv_mirror

  --- Logical volume ---
  LV Path                /dev/vg_mirror/lv_mirror
  LV Name                lv_mirror
  VG Name                vg_mirror
  LV UUID                SUI0os-ZfYw-ns5H-bnbz-UPf0-KHhv-CuemyB
  LV Write Access        read/write
  LV Creation host, time dlp.srv.world, 2022-07-07 15:07:33 +0900
  LV Status              available
  # open                 0
  LV Size                50.00 GiB
  Current LE             12800
  Mirrored volumes       2
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:6

[2]	If you'd like to set mirroring volume from a normal logical volume which is already running, Configure like follows.

# extend the volume group

[root@dlp ~]#

vgextend vg_data /dev/sdc1

  Volume group "vg_data" successfully extended

# set mirroring volume

[root@dlp ~]#

lvconvert -m1 /dev/vg_data/lv_data /dev/sdc1

Are you sure you want to convert linear LV vg_data/lv_data to raid1 with 2 images enhancing resilience? [y/n]: y
[ 2263.044511] device-mapper: raid: Device 1 specified for rebuild; clearing superblock
[ 2263.046045] device-mapper: raid: Superblocks created for new raid set
[ 2263.051592] md/raid1:mdX: active with 1 out of 2 mirrors
[ 2263.140399] mdX: bitmap file is out of date, doing full recovery
[ 2263.180629] md: recovery of RAID array mdX
  Logical volume vg_data/lv_data successfully converted.

# verify status

# complete to sync if [Cpy%Sync] turns to [100]

[root@dlp ~]#

lvs

  LV      VG      Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root    cs      -wi-ao---- 71.00g
  swap    cs      -wi-ao----  7.88g
  lv_data vg_data rwi-a-r--- 30.00g                                    15.70

[root@dlp ~]#

lvs

  LV      VG      Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  root    cs      -wi-ao---- 71.00g
  swap    cs      -wi-ao----  7.88g
  lv_data vg_data rwi-a-r--- 30.00g                                    100.00

[3]	Unset Mirroring Volume like follows if you want.

# specify -m0 to unset

[root@dlp ~]#

lvconvert -m0 /dev/vg_data/lv_data

Are you sure you want to convert raid1 LV vg_data/lv_data to type linear losing all resilience? [y/n]: y
  Logical volume vg_data/lv_data successfully converted.

[root@dlp ~]#

lvs -a -o vg_name,name,devices,size

  VG      LV      Devices         LSize
  cs      root    /dev/sda2(7990) 71.00g
  cs      root    /dev/sda2(2018) 71.00g
  cs      swap    /dev/sda2(0)     7.88g
  vg_data lv_data /dev/sdb1(0)    30.00g

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