[DRBD-user] Performance Issues after Upgrade

[Lars Ellenberg]

On Wed, Jun 23, 2004 at 04:43:36PM -0400, James W. Brinkerhoff wrote:
> On Wednesday 23 June 2004 03:28 pm, Helmut Wollmersdorfer wrote:
> > James W. Brinkerhoff schrieb:
> > > I upgraded to drbd 0.6.12 and it seems my performance has dropped like a
> > > stone.    System load runs very high (5.0 or above) and IO operations
> > > block often.
> >
> > Try
> >
> >    rm /var/lib/drbd/*
> >
> > before start.

unwise... only do this when you know what you are doing.
it _cannot_ have any effect on sync speed (unless you had a time skew,
and the drbd.conf.parsed is outdated...)

> > I needed this after upgrade 0.6.10 -> 0.6.12 to get a nice running drbd
> > at full speed of the link.


> 
> *NOTE* Sorry if there are multiple copies of this message...  My email client 
> refused to send them with the proper from address.
> 
> Did you also get those kernel errors?   I have 2 files in there...  
> drbd.conf.parsed (which has the same info as /etc/drbd.conf) and drbd0 which 
> is some binary file...        I'm a little reluctant to blow that away 
> without knowing what it is...     Both are dated from monday when I tried to 
> solve my problem by increasing tl-size (which did away with some of the 
> kernel errors, but not all and didn't solve the speed issues).

don't remove the binary file(s) in there.
that is drbd-0.6 persistent meta data. wizards only...

> This isn't speed on a Full Sync, but during normal writes...

the code change is that in 0.6.12 "write-hints" are sent non-blocking.
so sometimes they may be sent with a little delay.
before, kernel threads like pdflush or kupdated could have blocked on
this, and hang the system for a long time under certain timing
conditions. overall timing has changed, and some things made more noisy
(e.g. ko=some number).

search the archives around the release of 0.6.12 for more detail. 

	lge