[DRBD-user] running "the entire machine" off DRBD

Sunny sunyucong at gmail.com
Thu Sep 23 19:54:59 CEST 2010

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

Does DRBD use a different block scheme on disk? I thought it only adds
a small space for meta-data, right?

But anyway, running entire disk off drbd is not something you really
need, anyway, If you really want to fully cover your root system, you
can of course do this:

/sda1 --  Your /boot, contains kernels etc, you probably want to put a
static linked drbdadm as well
/sda5 == /dev/drbd1 --  Your / which is replicated to somewhere else by drbd1
/sda6 -- Your local swap partition

Modify initram-fs to load drbd module during boot time, and mount
drbd1 as /, just like the way as LVM and MD. You will need to
re-insert your drbd config to initramfs every-time you modify them,
LVM and MD in ubuntu have full set of script to automatically do that
for you.

One catch is that you need to be able to control drbd without your
root, so putting a static linked drbdadm in /boot , I imagine it would
definitely help when you need them.

On Thu, Sep 23, 2010 at 6:09 AM, Ian! D. Allen <idallen at idallen.ca> wrote:
> On Thu, Sep 23, 2010 at 07:32:56AM -0500, Alex Adriaanse wrote:
>> This is a failover setup where all data is replicated to a backup
>> server that's located offsite.  I'm not running the entire machine
>> from a DRBD disk because that means the root filesystem would have
>> to boot from the DRBD device.  Thus, the initrd image would have to
>> configure the drbd device, and that's not supported on Debian AFAIK.
> You can't run "an entire machine" off DRBD under any conditions, can you?
> Since a PC BIOS can't configure and start DRBD, the configuration and
> start has to be done by running a kernel loaded by the BIOS from a
> non-DRBD partition, which means something outside of DRBD has to boot
> up and then get DRBD started, at which point the machine can start using
> the DRBD stuff.
> Some little piece of the system has to remain outside of DRBD for the
> BIOS to boot and to get DRBD started, and that applies to any Linux
> distribution, not just Debian.  If you want full back-up of your "entire
> machine", that part of the system that is outside DRBD (the part that
> actually boots the machine and starts DRBD) has to be copied to the
> backup machine by other means.  You can try to make this kernel and its
> associated file system as small as possible, but you can't eliminate it.
> Am I right?
> --
> | Ian! D. Allen  -  idallen at idallen.ca  -  Ottawa, Ontario, Canada
> | Home Page: http://idallen.com/   Contact Improv: http://contactimprov.ca/
> | College professor (Free/Libre GNU+Linux) at: http://teaching.idallen.com/
> | Defend digital freedom:  http://eff.org/  and have fun:  http://fools.ca/
> _______________________________________________
> drbd-user mailing list
> drbd-user at lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user

More information about the drbd-user mailing list