[DRBD-user] Implementing drbd with an existing filesystem

Federico Sevilla III jijo at free.net.ph
Fri Mar 11 00:35:11 CET 2005

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

On Thu, Mar 10, 2005 at 10:15:02AM -0600, kmoogle wrote:
> I currently have a 1TB NFS server with an IDE boot drive (/dev/hda)
> and a 3ware-based RAID10 (/dev/sda) containing existing customer data.
> For redundancy, we have purchased a second 1TB server with a single
> 3ware-based RAID10 (no IDE boot drive). Data is currently replicated
> using rsync nightly.
> I'm interested in using drbd, but cannot modify the active fileserver
> with customer data outside of perhaps replacing the kernel. No major
> (or potentially destructive) modifications can be made to the primary,
> active server.
> Can I implement drdb without adversely affecting the primary
> fileserver? What changes would I need to make to the existing
> filesystems (if any) to either the primary or secondary in order to
> implement drbd?

No, I don't think you can implement DRBD without doing anything drastic.
An acceptable approach may be to set up DRBD and Heartbeat on the
current backup fileserver, treating it as a "new" server with DRBD+HA
but with a "missing" partner. You can battle test this in the lab
pre-deployment, and then schedule maintainance downtime to replace the
current fileserver with this "new" server. After this new server has
stabilized as a replacement active fileserver, with DRBD+HA albeit with
a "missing" partner, you can tear down the current active fileserver,
set it up with DRBD+HA to match the new active fileserver but as its
partner with DRBD+HA, then you can deploy it.

This setup gives you a failover system with realtime data mirroring,
which, depending on your setup and objectives, may be desirable and
worth all the hassle you'll have to go through.

 --> Jijo

Federico Sevilla III : jijo.free.net.ph : When we speak of free software
GNU/Linux Specialist : GnuPG 0x93B746BE : we refer to freedom, not price.

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