Posts Tagged ‘Cluster LVM’
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
Unix, AIX, Linux, Storage Disk, Storage Area Network (SAN), HMC, Blade Center, IBM, TI, SysAdmin, Computação e Pessoal
UNIX (Linux, AIX, Solaris, HP-UX) Specialist at TIVIT
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Kairo Araujo 