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Date:      Sat, 3 Dec 2016 09:43:38 -0500
From:      Robert Blayzor <rblayzor.bulk@inoc.net>
To:        FreeBSD Stable <freebsd-stable@freebsd.org>
Subject:   Re: CARP master election changed in 11.0 ?
Message-ID:  <AD0462DE-3685-48B3-92B3-BF1B90B15D44@inoc.net>
In-Reply-To: <B7463704-11F2-4CD8-B66D-C99A7A482D1A@inoc.net>
References:  <B7463704-11F2-4CD8-B66D-C99A7A482D1A@inoc.net>

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Disregard, this problem has been semi-solved. For reasons unknown now it =
was due to carp send error penalties being applied to one of the =
servers, which are added to the advskew.

Since a lagg interface is involved:

carp: demoted by 10 to 10 (send error 50 on lagg0)
carp: demoted by 10 to 20 (send error 50 on lagg0)


But what is strange is that the two servers in the VHID have the same =
exact hardware. Experiencing this send error on one but not the other=E2=80=
=A6

Ultimately the work around was adjusting
net.inet.carp.senderr_demotion_factor -> 10

=46rom it=E2=80=99s default of 240.


Since these errors appear only at startup and not incrementing, it =
doesn=E2=80=99t really look like a problem.


net.inet.carp.ifdown_demotion_factor: 240
net.inet.carp.senderr_demotion_factor: 10
net.inet.carp.demotion: 20


--
inoc.net!rblayzor
XMPP: rblayzor.AT.inoc.net
PGP Key: 78BEDCE1 @ pgp.mit.edu









> On Dec 1, 2016, at 3:10 PM, Robert Blayzor <rblayzor.bulk@inoc.net> =
wrote:
>=20
> Did something change between 10.x and 11.0 with carp MASTER election =
and advskew?=20
>=20
> I have several 10.3 servers where the master is elected based on the =
member with the LOWEST advskew.
>=20
> =46rom a pair of 10.3 servers:
>=20
> 	vlan: 100 parent interface: lagg0
> 	carp: MASTER vhid 10 advbase 1 advskew 100
>=20
> 	vlan: 100 parent interface: lagg0
> 	carp: BACKUP vhid 10 advbase 1 advskew 110
>=20
>=20
> Deploying a new pair of 11.0-RELEASE servers, I see the opposite; =
seems like the member with the HIGHEST advskew wins now:
>=20
>=20
>        carp: BACKUP vhid 20 advbase 1 advskew 0
> 	groups: lagg
>=20
> 	carp: MASTER vhid 20 advbase 1 advskew 100
> 	groups: lagg
>=20
>=20
>=20
> Preemption doesn=E2=80=99t seem to matter, even with preemption =
enabled. (which it is).
>=20
> =46rom OpenBSD, man reads:
>=20
> advskew
> This optional parameter specifies how much to skew the advbase when =
sending CARP advertisements. By manipulating advskew, the master CARP =
host can be chosen. The higher the number, the less preferred the host =
will be when choosing a master. The default is 0. Acceptable values are =
from 0 to 254.
>=20
>=20
> And this seems true in 10.3 but reversed in 11.0 ?
>=20
> --
> inoc.net!rblayzor
> XMPP: rblayzor.AT.inoc.net
> PGP Key: 78BEDCE1 @ pgp.mit.edu
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
> _______________________________________________
> freebsd-stable@freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-stable
> To unsubscribe, send any mail to =
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