Centos5: OCFS2 cluster FS on dual primary DRBD: part 1 – prepare LVM on RAID1

A while ago I promised to you ( and myself) to publish the instruction on how to setup OCFS2 cluster fs for 2 nodes over DRBD dual primary configuration. Now it’s time.
I am going to split it over multiple posts to cover as many details as possible.
This is part 1 – laying the foundation – LVM over RAID1 setup.

Prerequisites: 2 Centos5 servers with identical disk configuration
Time: up to 30 minuts (depends on shared disk size and network speed)
Skill level required: Advanced (means you understand the difference between apache and kernel modules and not afraid of command line – this is called advanced nowdays).

To start we will be configuring DRBD on top of LVM which is configured on top of RAID1. The reasons are – LVM means scalability, so some time down the line we can add more PVs to expand the configured disk. RAID1 – reliability with slight performance improvement on read.
On both servers node1 and node2 we have /dev/md5 – identical raid1 arrays. For simplicity sake we will create 1 logical volume shared that takes 100% of space on volume group vg0
1. Creating physical volume

# >
pvcreate /dev/md5
# >
pvdisplay
  --- Physical volume ---
  PV Name               /dev/md5
  VG Name               vg0
  PV Size               892.35 GB / not usable 3.38 MB
  Allocatable           yes (but full)
  PE Size (KByte)       4096
  Total PE              228441
  Free PE               0
  Allocated PE          228441
  PV UUID               sMWW6Z-5aIJ-hSuq-kvpn-jCgT-rT2A-UCwOFD

2. Creating volume group vg0 on this physical volume

#>
 vgcreate vg0 /dev/md5
#>
 vgdisplay
  --- Volume group ---
  VG Name               vg0
  System ID            
  Format                lvm2
  Metadata Areas        1
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                1
  Open LV               1
  Max PV                0
  Cur PV                1
  Act PV                1
  VG Size               892.35 GB
  PE Size               4.00 MB
  Total PE              228441
  Alloc PE / Size       228441 / 892.35 GB
  Free  PE / Size       0 / 0  
  VG UUID               uCDZhY-igFW-2DLb-XOOM-IUqT-Zfox-VdtKjA

3. Creating logical volume shared on volume group vg0

#>
 lvcreate -l100%VG -nshared vg0
#>
 lvdisplay

  --- Logical volume ---
  LV Name                /dev/vg0/shared
  VG Name                vg0
  LV UUID                2OZACr-UCLV-iLUg-cWdG-vZS6-sXyX-d9dq3T
  LV Write Access        read/write
  LV Status              available
  # open                 2
  LV Size                892.35 GB
  Current LE             228441
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:0

All done for now.
Please stay tuned for the next articles in this series – I intended to finish the instructions with working dual node OCFS2 cluster setup.

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