[DRBD-user] DRBD write throughput very very bad

Lars Ellenberg lars.ellenberg at linbit.com
Fri Apr 24 10:42:10 CEST 2009

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

On Fri, Apr 24, 2009 at 08:46:12AM +0200, Tobias Appel wrote:
> Thanks for these options. I did read up on them and I want to disable 
> all of those since I have a battery backed controller.
> Currently in my config in the disk section I only have:
> disk {
> on-io-error detach;
> }
> when I tried adding any of those options listed by you I received an 
> error like this:
> /etc/drbd.conf:25: Parse error: 'an option keyword' expected,
> 	but got 'no-disk-barrier'
> Starting DRBD resources:    /etc/drbd.conf:25: Parse error: 'an option 
> keyword' expected,
> And also I did not find any "wo:" when running cat /proc/drbd | grep wo
> Is it because my version is too old? I'm using 8.0.14 but according to 
> the documentation it should be available since 8.0.9.

the users guide is always for the current release of DRBD,
which is 8.3.1 at the time of writing this email.

the "wo:" thing is only available in 8.3 (since 8.2.something) it was
introduced when the barrier method has been introduced, at the same time
as the explicit "drain" and "none" methods have been introduced.

drbd 8.0 has only the concept of drain,
and since 8.0.9 the "flush" concept.
in 8.0 you can only disable the "flush",
which means you get "drain".

the documentation is correct, though maybe misleading.
drain was the only concept implemented before 8.0.9.
that does not mean all other methods have been introduced with 8.0.9.
e.g. options to disable the flush method again have only been
introduced with 8.0.12.  (as written in the changelog)

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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