Comment 18 for bug 8392

Message-ID: <email address hidden>
Date: Tue, 9 Nov 2004 07:29:08 -0500
From: Stephen Frost <email address hidden>
To: Doug Winter <email address hidden>, <email address hidden>
Cc: Torsten Landschoff <email address hidden>
Subject: Re: [debian-openldap] Bug#272984: slapd: checkpoint directive missed from bdb backend

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* Doug Winter (<email address hidden>) wrote:
> Torsten Landschoff wrote:
> >I've read up on Berkeley DB transactions and it seems to me that it
> >would make sense to write a checkpoint from time to time. No data should
> >be lost but in the default configuration slapd only checkpoints the DB
> >during shutdown which means that reopening the database after a crash=20
> >(which looks for me like the only reason why slapd would go down short
> >of a system reboot) will take a lot of time wading through old log
> >files.
> >
> >I don't want to mess with the slapd defaults for this small problem
> >though and I wonder what upstream has to say. AFAICT the checkpoint
> >directive leads to a massive breakdown of write performance for not that=
=20
> >much gain.=20
>=20
> I have lost significant data because this directive wasn't in the=20
> logfile, and I didn't know how to recover a berkeley db. The third=20
> time this happened I spent several hours reading up on it and managed to=
=20
> get my data back. If slapd or the system crashes (in this case it was=20
> because of a power outage), then the database needs to be manually=20
> recovered.
>=20
> It doesn't happen automatically, so can lead to data loss if the=20
> database is not recovered.

The point is that the database *can* be recovered unless something worse
has happened (such as file system corruption). Just because you can't
open it immediately upon reboot doesn't mean the data has been lost.
Torsten, perhaps we could add something to the README about how to use a
Berkley db, with some URLs to more documentation.

 Stephen

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