Re: OpenLDAP Mirror Mode configuration

[Mathieu MILLET <ldap@htam.net>]

On Thu, 25 Jun 2009 07:41:42 -0600, Matt Kassawara <battery@writeme.com>
wrote:
> I'm running mirror mode on a pair of VMs and haven't noticed any issues
> with
> replication.  If you're using VMware ESX/ESXi 3.5, I recommend
configuring
> Linux guests with the kernel boot parameter "clocksource=acpi_pm" and
> configuring VMware Tools to handle clock management in the guest.  Verify
> NTP isn't running in the guest.  Also, making sure the Linux kernel
> periodic
> interrupt timer runs at 100 Hz instead of 250 or 1000 Hz can reduce
timing
> issues.  VMware provides some documentation on best practices for
> performance tuning I'd recommend reading.

Yes, I have read these (but was using VM workstation). Also, My
experimentation was during last summer 2008 and at the same period VMWare
switch from "DO NOT USE NTP in Guest, instead VmwareTools" to "Use NTP"
without any explanation ...

The main trouble was when modifying on both side "too quickly".

Other testings with differents applications show up that virtualization is
no good for timing-picky application (but it is going off-topic ;)

Thanks for the sharing.

Sincerely yours, Mathieu.

> On Thu, Jun 25, 2009 at 12:16 AM, Mathieu MILLET <ldap@htam.net> wrote:
> 
>> On Tue, 23 Jun 2009 09:36:23 +0100, Fernando Silva
>> <fernandolrsilva@gmail.com> wrote:
>> > Hi all,
>>
>> Hi
>>
>> > I'm trying to setup a Mirror Mode configuration using 2 machines
>> > running
>> > OpenLDAP v2.4.11 on both. To make things easy both machines are on the
>> > same (private) network.
>> >
>> > [snip]
>> > mirrormode on
>> >
>> > I'm using Ubuntu 8.10 inside a VMWare image, but both images are
>> > running
>> > on independent machines and the network on both is Bridge Mode.
>>
>> >From previous experiment, especially with OpenLDAP 2.4.11, I have very
>> hard
>> time with making OpenLDAP N-way replication working on VM, especially
>> VMWare-based ones.
>>
>> The main problem was with the management of the system clock, where
>> VMWare
>> was making the clock slower and then make a "jump" to compensate the
>> slowiness. So, I got a lot of line "new modification with older timer
>> value" (can't remember the precise log line, though).
>>
>> I had to switch to plain physical server (which was my target by then).
>>
>> > All
>> > seems well according to OpenLDAP manual, but maybe I'm missing
>> > something. I start both servers using "slapd -d sync" in order to
>> > filter
>> > only the sync part.
>> >
>> > I created a script to insert 200 employees in my directory, to force
>> > the
>> > servers to sync up. When I start both servers and insert the employees
>> > in machine 1, I get this too much lines with this sample:
>> > slap_queue_csn: queing 0xb6851b4a
>> 20090623082909.571025Z#000000#000#000000
>> > slap_graduate_commit_csn: removing 0xb82165c8
>> > 20090623082909.571025Z#000000#000#000000
>> >
>> > So the CSN is being created (I think), but there's no sync to machine
>> > 2,
>> > which makes me frustated. . .
>> >
>> > I'd appreciate any comments you can have, especially if you already
>> > have
>> > this kind of setup running.
>> >
>> > Best regards,
>> > Fernando
>>
>> Hope it can help.
>> Sincerely yours, Mathieu MILLET.
>>
>>