DRBD on Fedora 13
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This article covers installing and configuring DRBD on a two-node Fedora 13 cluster.
DRBD is useful in small clusters as it provides real-time mirroring of data across two (or more) nodes. In two-node clusters, this can be used to host clustered LVM physical volumes. On these volumes you can create logical volumes to host GFS2 partitions, virtual machines, iSCSI and so forth.
yum install drbd.x86_64 drbd-xen.x86_64
PV /dev/sda2 VG vg01 lvm2 [465.50 GiB / 424.44 GiB free] Total: 1 [465.50 GiB] / in use: 1 [465.50 GiB] / in no VG: 0 [0 ]
On my nodes, each of which has a single 500GB drive, I've allocated only 20GB to dom0 so I've got over 440GB left free. I like to leave a bit of space unallocated because I never know where I might need it, so I will allocate 400GB even to DRBD and keep the remaining 44GB set aside for future growth. The space you have left and how you want to allocate is an exercise you must settle based on your own needs.
Next, check that the name you will give to the new LV isn't used yet. The lvscan tool will show you what names have been used.
ACTIVE '/dev/vg01/lv_root' [39.06 GiB] inherit ACTIVE '/dev/vg01/lv_swap' [2.00 GiB] inherit
We see from the above output that lv_root and lv_swap are used, so we will use lv_drbd for the DRBD partition. Of course, you can use pretty much any name you want.
Now that we know that we want to create a 400GB logical volume called lv_drbd, we can proceed.
Now to create the logical volume for the DRBD device on each node. The next two commands show what I need to call on my nodes. If you've used different names of have a different amount of free space, be sure to edit the following arguments to match your nodes.
lvcreate -L 400G -n lv_drbd /dev/vg01
Logical volume "lv_drbd" created
If I re-run lvscan now, I will see the new volume:
ACTIVE '/dev/vg01/lv_root' [39.06 GiB] inherit ACTIVE '/dev/vg01/lv_swap' [2.00 GiB] inherit ACTIVE '/dev/vg01/lv_drbd' [400.00 GiB] inherit
We can now proceed with the DRBD setup!
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