Making LVM Mirror on Linux using Red Hat CLuster Suite – CLVM (Cluster LVM) – on RHEL 5


1. The scenario

On my box I’ve two disks from two differents Storage Disk.

Using multipath I’ve this disks
/dev/dm-15 from Storage Disk A (in use)
/dev/dm-28 from Storage Disk B (not in use yet.)

I’ve the Volume Group with name vg_gfs00 on /dev/dm-15
I’ve the Logical Volume with name lv00 on the Volume Group VG_GFS

Looking my outputs pvs, vgs and lvs

PVS output
# pvs
PV         VG          Fmt  Attr PSize   PFree
/dev/dm-15 vg_gfs00    lvm2 a-   278,98G 39,95G
/dev/sda3  rootvg      lvm2 a-   131,47G 86,19G

VGS output
# vgs
VG          #PV #LV #SN Attr   VSize   VFree
rootvg        1  11   0 wz--n- 131,47G 86,19G
vg_gfs00all   8   7   0 wz--n- 278,98G 39,95G

LVS output
# lvs
LV          VG          Attr   LSize
homelv      rootvg      -wi-ao 512,00M
optlv       rootvg      -wi-ao   1,00G
rootlv      rootvg      -wi-ao   1,00G
tmplv       rootvg      -wi-ao   2,00G
usrlv       rootvg      -wi-ao   4,00G
varloglv    rootvg      -wi-ao   8,00G
varlv       rootvg      -wi-ao   4,00G
lv00        vg_gfs00    -wi-ao 239,03G

2. Objective

Implement a mirror on filesystems for high availbility if my Storage Disk A or B crashs.

3. Implementing

a. Make a PV on new disk (/dev/dm-28)

# pvcreate /dev/dm-28

b. Add new volume on the vg_gfs00

# vgextend vg_gfs00 /dev/dm-28

c. Make a mirror on Logical Volume

# lvconvert -m1 vg_gfs00/lv00 /dev/dm-28
vg_gfs00/lv00: Converted: 17,1%
vg_gfs00/lv00: Converted: 34,1%
vg_gfs00/lv00: Converted: 51,0%
vg_gfs00/lv00: Converted: 68,4%
vg_gfs00/lv00: Converted: 85,5%
vg_gfs00/lv00: Converted: 100,0%

Note: If your LV are in more PVs you can specify all PVs
Sample:

# lvs -a -o +devices | grep lv00
lv00          vg_gfs00 -wi-ao  10,00G     /dev/dm-15(0)
lv00          vg_gfs00 -wi-ao  10,00G     /dev/dm-16(123490)

In this case dm-15 and dm-16 are on my Storage Disk A, I need two disks on the Storage Disk B, sample dm-28 and dm-29.
For convert I use this
# lvconvert -m1 vg_gfs00/lv00 /dev/dm-28 /dev/dm-29

d. Checking Mirror with lvs -a -o +devices

# lvs -a -o +devices | grep vl00
lv00            vg_gfs00 mwi-ao  10,00G       lv00_mlog 100,00         lv00_mimage_0(0),lv00_mimage_1(0)
[lv00_mimage_0] vg_gfs00 iwi-ao  10,00G                                /dev/dm-15(10242)
[lv00_mimage_1] vg_gfs00 iwi-ao  10,00G                                /dev/dm-28(14086)

Looking details:

lv00 is a lv00_mlog and have a 100% of sync to lv00_mimage_0 and lv00_image1.
The lv00_mimage_0 is stored on /dev/dm-15
The lv00_mimage_1 is stored on /dev/dm-28

Looking with a simple lvs

# lvs
LV          VG          Attr   LSize  Origin Snap%  Move Log              Copy%  Convert
homelv      rootvg      -wi-ao 512,00M
optlv       rootvg      -wi-ao   1,00G
rootlv      rootvg      -wi-ao   1,00G
tmplv       rootvg      -wi-ao   2,00G
usrlv       rootvg      -wi-ao   4,00G
varloglv    rootvg      -wi-ao   8,00G
varlv       rootvg      -wi-ao   4,00G
lv00        vg_gfs00    -wi-ao 239,03G              lv00_mlog 100,00

If the lv00_mlog is not 100% you have a problem with one of disks.

4. Documentation:

* http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.2/html/Cluster_Logical_Volume_Manager/
– 2.3.3. Mirrored Logical Volumes
– 4.4.1.3. Creating Mirrored Volumes
– 6.3. Recovering from LVM Mirror Failure

Anúncios

  1. Igor

    Kairo, tudo jóia meu amigo, ta sumido heim.

    Rapaz, quando der aparece no msn para conversarmos, estou precisando muito falar com você.

    Sou eu o Igor ( Bigu ) LEMBRA … meu msn voce tem b1gu@hotmail.com.

    Não deixe de me procurar. Grande abs.

  2. Michael

    Interesting, thanks.

  3. Muito legal!

    Seria interessante você escrever sobre o caso do rootvg sofrer failure como recuperar o sistema através de outro disco no mirror.

    Atenciosamente.

  4. sepp rapper

    is it possible with 4 disks (2 from SAN A and 2 from SAN B)?




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