[DRBD-user] Oracle virtual disk file (vdi) replication with DRBD

Lars Ellenberg lars.ellenberg at linbit.com
Tue May 9 10:38:12 CEST 2017

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Sun, May 07, 2017 at 08:56:10AM +0000, Dirk Lehmann wrote:
> Dear Sir or Madame,
> I was wondering if somebody would let me know if it is
> unproblematicaly possible to place the Oracle virtual disk file on the
> drbd drive and access this file on the drbd drive parallely from two
> running hypervisors to "mirror" the virtual machine on different hosts
> to get the vm ha without conflicting when the master host has changes
> in his virtual machine?

>From the "replication" and "failover clustering" perspective,
there is nothing special about VDI files.

VDI files are, well, files.

DRBD is a block device.

In theory, you could put the file directly on the block device,
but usually no application would understand that.

So you put a file system on top of the block device,
mount that file system,
and put the files inside that file system.

To be able to failover,
there is no special requirement,
but you can not have "normal" file systems
mounted and accessible on several hosts concurrently,
you need to exclusively activate and mount it.

If you think you need to mount that concurrently on two hosts,
you could use a cluster file system such as GFS2 or OCFS2.

Or use an NFS failover cluster, export your files via NFS,
and access that from serveral hosts.

You could use "raw" devices instead of "files",
that would get rid of the file system layer.

Probably more options.

What is "best" depends on your use case,
and choices you make about performance, convenience, robustness,
complexity, flexibility, managability of the setup. 

Does not really help you now, does it?

: Lars Ellenberg
: LINBIT | Keeping the Digital World Running
: DRBD -- Heartbeat -- Corosync -- Pacemaker

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