---- Original message ----
Date: Mon, 09 Feb 2009 08:08:32 -0800 From: Quanah Gibson-Mount quanah@zimbra.com Subject: Re: How to set BDB "read-only" before slapcat command ? To: Andrew Hall whippyhubbles@googlemail.com,Michael Ströder michael@stroeder.com Cc: openldap-technical@openldap.org
--On Monday, February 09, 2009 3:44 PM +0000 Andrew Hall whippyhubbles@googlemail.com wrote:
The possible problem I see with that setup is what happens if the slapcat occurs during an update from the provider to the consumer ?
I'm not sure why you feel it is necessary to set the server read-only before you run slapcat anyway. Do you actually have a process that knows exactly what changes occurred in any given second, so that, if say, your backup starts at 1:00:00, you can then replay all the changes from that point in time?
If you do, then it doesn't matter whether or not it was in read-only. Simply replay the changes. If you don't, then it doesn't matter whether or not it was in read-only, because you don't know what changes happened after that point.
I honestly am not aware of anyone who bothers to put their DB into read-only before slapcatting, although they may be out there.
Admittedly we stop one slapd in our group of servers (usually a master) to take a point in time snapshot with slapcat, then simply restart it. It is used solely as part of our disaster recovery. In the event of BDB corruption that is unrecoverable, we can build a new server from the full-text export.
Just basic DBA paranoia policy. :-) :-)
Cheers, Bill
--On Monday, February 09, 2009 12:06 PM -0500 William Jojo w.jojo@hvcc.edu wrote:
Admittedly we stop one slapd in our group of servers (usually a master) to take a point in time snapshot with slapcat, then simply restart it. It is used solely as part of our disaster recovery. In the event of BDB corruption that is unrecoverable, we can build a new server from the full-text export.
Just basic DBA paranoia policy. :-) :-)
Sure, but still, if require you have point in time, it's only useful if you can get from there to another point in time. I.e., if all you need is a backup, then putting it into read-only vs. not read-only doesn't matter, because you'll always get a snapshot of the DB. The only time (IMHO) it matters to have read-only is if you need to know how the database looked exactly at a point in time so you can get it to another point in time, and if you can do that, then you already have the tools to replay the changes, and could just ignore any that were applied during the slapcat if it wasn't in RO mode.
Shutting down slapd as a paranoia thing is something a bit different, although it does enforce RO mode. ;)
--Quanah
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Quanah Gibson-Mount Principal Software Engineer Zimbra, Inc -------------------- Zimbra :: the leader in open source messaging and collaboration
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Quanah Gibson-Mount -
William Jojo