[DRBD-user] using DRBD with md0 as system disk

Lars Ellenberg Lars.Ellenberg at linbit.com
Fri Apr 2 11:19:29 CEST 2004

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

/ 2004-04-01 13:44:54 -0800
\ Jason Gray:
> I've recently setup a Software RAID on a RH 9.0 box using two devices
> (/dev/hdg /dev/hde) that are combines to create /dev/md0 and /dev/md1.  The
> system is on /dev/md1 and the /boot partition is on /dev/md0.  Is it
> possible to use DRBD on these RAID devices?  I'm not sure that it is since
> DRBD needs to make use of a virtual device (/dev/nb0) and map to a real
> device (/dev/hdg).  And since /dev/hdg and /dev/hde are already part of the
> RAID then I have no spare disks to use.

No problem with DRBD on top of MD.

> Also, since my system is on the
> RAID the DRBD module can't be loaded until the system is up and vice versa.

Well, while booting, you do not yet know which node has the good data.
So using DRBD below a file system you need to boot the box ("/boot", "/", ...)
is not posible without further tweaks, and not really useful anyways.

There are different tools for different tasks. How often do you expect
the content of /boot to change?  See?  And why would you want to mirror
its "frequent changes" over to the other box in real time then?

> Is there a way around this?

Have the modules you need to boot the box in the initrd.

	Lars Ellenberg

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