One of the projects that LINBIT will publish soon[1. With an Open Source license; GIT will be the preferred way to help us.] is
drbdmanage, which allows easy cluster-wide storage administration with DRBD 9.
Every DRBD user knows the drill – create an LV, write a DRBD resource configuration file,
up, initial sync, …
But that is no more.
The new way is this:
drbdmanage new-volume r0 50 deploy 4, and here comes your quadruple replicated 50 gigabyte DRBD volume.
This is accomplished by a cluster-wide DRBD volume that holds some
drbdmanage data, and a daemon on each node that receives DRBD events from the kernel.
Every time some configuration change is wanted,
drbdmanagewrites into the common volume,
- causing the other nodes to see the
- so that they know to reload the new configuration,
- and act upon it – creating or removing an LV, reconfiguring DRBD, etc.
- and, if required, cause an initial sync.
As DRBD 8.4.4 now supports DISCARD/TRIM, the initial sync (on SSDs or Thin LVM) is essentially free – a few seconds is all it takes. (See eg.
mkfs.ext4 for a possible user).
Further usecases are various projects that can benefit by a “shared storage” layer – like oVirt, OpenStack, libVirt, etc.
Just imagine using a non-cluster-aware tool like
virt-manager to create a new VM, and the storage gets automatically sync’ed across multiple nodes…
Interested? You’ll have to wait for a few weeks, but you can always drop us a line.