[DRBD-user] size in drbd.conf and size of drbd0 should be the same?

Alex linux at vfemail.net
Thu Aug 28 10:57:56 CEST 2008

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

On Thursday 28 August 2008 04:03, you wrote:
> On Aug 27, 2008, at 12:49 AM, Alex wrote:
> > On both machines, in drbd.conf i have:
> >
> > disk {
> >  on-io-error detach;
> >  size 18G;
> > }
> [...]
> > Questions:
> > 1. which size is correct for drbd0 device: 18GB or 19.3GB?
> > 2. which directive is valid to be used inside disk {} section of
> > drbd.conf:
> > "size" or "disk-size"?
> Why use either one?  It works fine without them.  I don't even see
> either one of these in man 5 drbd.conf...

Is on drbd documentation:


This section is used to fine tune DRBD's properties in respect to the low 
level storage. Please refer to drbdsetup(8) for detailed description of the 

Optional parameter: on-io-error, size, ...
[end snip]

And i am using it to have better control over drbd devices. I am running LVM 
on top of drbd0 and GFS on top of LVM. GFS does not support shrinking. In any 
scenario, I don't want to be suprissed when i'm replacing disks and drbd are 
resizing drbd0 on the fly. GFS could be corrupted. Even if disks (raid5 or 
raid6 arrays) will be the same in size, this is not a must to be identical. 
So, shortly, i don't want to give permission to drbd to adjust the size on 
the fly (to avoid shrinking). I want to have full controll regarding drbd 
size and all the time i am setting it in drbd.conf with 5-10% less then 
minimum available hardware size available on our nodes.

And my question comes naturally, because i want to be sure that i am using the 
correct syntax. Probably, "size" directive is the correct one to be used in 
newer drbd versions and "disk-size" syntax is deprecated (has been used on 
old drbd implementations).

Can somebody clarify this aspect?


More information about the drbd-user mailing list