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

Alex linux at vfemail.net
Fri Aug 29 15:39:10 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 Friday 29 August 2008 13:49, Böttcher, Matthias wrote:
> > -----Original Message-----
> > From: Alex <linux at vfemail.net>
> > Sent: Friday, August 29, 2008 9:22 AM
> > To: <drbd-user at lists.linbit.com>
> > Subject: Re: [DRBD-user] size in drbd.conf and size of drbd0 should be
> > thesame?
> [...]
> > Our topic here is: WHY SIZE in drbd.conf and size of /dev/drbd0
> > are different and which size is correct: the one in drbd.conf
> > 18GB or the one reported by fdisk: 19.3GB?
> Both are correct.
> >  Why we have this difference?
> We haven't any difference.
> Please take a look at the definitions of GB (gigabyte)
> http://en.wikipedia.org/wiki/Gigabyte

Hi Mattias,

As is specifyed in link posted by you, since 1999, IEC recommends that this 
unit (1024*1024*1024) should instead be called a gibibyte and to be 
abbreviated GiB, to avoid confusions!

> drbd assumes: "1 gigabyte = 1024^3 bytes = 1,073,741,824 bytes"
> and: "18 gigabytes = 18 * 1024^3 bytes = 19,327,352,832 bytes"

... here we are talking about GiB...

> fdisk assumes: "1 gigabyte = 1,000,000,000 bytes"

... and here, about GB!

GiB != GB

So, at the end, is right to say that i created a fixed size of 18GiB and not a 
18GB (which is wrong) in drbd.conf which is equivalent with 19.3GB size 
reported by fdisk!

18GiB is always equivalent with 19.3GB!
18GB will never be equal or equivalent with 19.3GB!

Drbd documentation is wrong when talking about GB and not GiB ... Maybe is 
better to be added a new question in DRBD FAQ pointing to $subj, in order 
avoid future usage confussions!


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