Re: Openldap 2.3.11 cannot autorecover from abnormal shutdown.

[Howard Chu <hyc@symas.com>]

Yingbo Qiu wrote:
> Thanks for your explaining.
>
> We are a software vendor providing web-mail system solution and
> OpenLDAP is a part of the solution. We must be sure that customer's
> machine could successful startup(incluing openldap) after a power
> failure. Because the OpenLDAP 2.0.27 with back-gdbm have no problem
> under this environment, we must keep the newer version's stability.
>   

You are quite mistaken. OpenLDAP 2.0.27 is highly unstable, even moreso 
with gdbm. You just don't see it because there is no error detection in 
that code. The fact that it is willing to startup when the database is 
in a corrupted state is not doing anyone any favors.

> I just want to decide add a 'db_recover' in the init script. Now I
> have another question: when will slapd write the environment headers?
> Farther, can you sure slapd should autorecover correctly after writing
> environment?
>   

As the BerkeleyDB documentation clearly states, there are no guarantees 
when the hardware fails.
> 2005/12/20, Howard Chu <hyc@symas.com>:
>   
> > Sounds like you lost power before the disk drive actually wrote the
> > environment pages to disk.
> > Again, read the BerkeleyDB documentation.
> > http://www.sleepycat.com/docs/ref/program/cache.html
> >
> > There's no magic - if your system loses power before the disks finish
> > writing the data, the data is lost. If the power fails before the
> > environment headers are written, then the environment is useless, and
> > there is nothing to recover.
> >
> > I believe this email thread has gone as far as it can. Don't be stupid:
> > no amount of software can correct for catastrophic hardware failures -
> > invest in an uninterruptible power supply.
> >
> > Yingbo Qiu wrote:
> >     
> > > > Read the BerkeleyDB documentation. "db_stat -e" will print the
> > > > environment version along with other information.
> > > >         


--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/