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Today's Topics:
1. Re: General questions about failover, config changes and
restarting (James Dore)
2. Re: General questions about failover, config changes and
restarting (James Dore)
----------------------------------------------------------------------
Message: 1
Date: Fri, 4 Mar 2016 10:58:22 +0000
From: James Dore <[email protected]>
To: "[email protected]" <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: General questions about failover, config changes and
restarting
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
> On 3 Mar 2016, at 21:15, [email protected] wrote:
>
>>> Sync is finished when both peers return to NORMAL mode. You need to
>>> restart both servers (just kill dhcpd and restart it) one after
>>> another or you're likely to run into issues with the pools not
>>> matching, and then you'll run into issues with not leasing IPs.
> ...
>> Any ideas why my servers need so many restarts? I try to leave them to
>> settle for five or six minutes before trying again, but they just seem to
>> stick with things like
>
> I am somewhat mystified about why you would need many minutes for a
> restart. Here's what we see on our failover pair, with around 100k
> leases and a couple of hundred pools:
>
> (master restarts, log on slave):
> Mar 3 08:50:00 slam dhcpd: peer dhcp1-dhcp2: disconnected
> Mar 3 08:50:00 slam dhcpd: failover peer dhcp1-dhcp2: I move from normal to
> communications-interrupted
> ...
> (a few seconds pass, and then)
> Mar 3 08:50:11 slam dhcpd: failover peer dhcp1-dhcp2: peer moves from normal
> to normal
> Mar 3 08:50:11 slam dhcpd: failover peer dhcp1-dhcp2: I move from
> communications-interrupted to normal
>
> So a restart for us takes around 11 seconds.
>
> It should be noted that
> - The servers have plenty of memory, and hardware RAID with battery
> backup for the disks.
> - We use the "delayed ACK" facility.
>
> Steinar Haug, Nethelp consulting, [email protected]
Sorry, clearly I didn?t explain myself clearly enough: it?s not that the
restart *itself* that takes minutes (that takes a couple of seconds) - it?s the
period of time *after* the restart in which the peers are sat not synchronising
or sitting in partner-down/recover/recover wait state and *before* I do another
restart that kicks them back into sync.
Hope that makes sense!
Cheers,
James
------------------------------
Message: 2
Date: Fri, 4 Mar 2016 11:00:01 +0000
From: James Dore <[email protected]>
To: Users of ISC DHCP <[email protected]>
Subject: Re: General questions about failover, config changes and
restarting
Message-ID: <[email protected]>
Content-Type: text/plain; charset="utf-8"
> On 3 Mar 2016, at 16:45, S Carr <[email protected]> wrote:
>
> On 3 March 2016 at 15:02, James Dore <[email protected]> wrote:
>> Any ideas why my servers need so many restarts? I try to leave them to
>> settle for five or six minutes before trying again, but they just seem to
>> stick with things like
>>
>> dhcpd.log-20151123:2015-11-23T10:17:58.203346+00:00 garibaldi dhcpd:
>> failover peer newc-dhcp: I move from normal to shutdown
>> dhcpd.log-20151123:2015-11-23T10:18:03.848105+00:00 garibaldi dhcpd:
>> failover peer newc-dhcp: I move from shutdown to startup
>> dhcpd.log-20151123:2015-11-23T10:18:03.854208+00:00 garibaldi dhcpd:
>> failover peer newc-dhcp: peer moves from normal to communications-interrupted
>> dhcpd.log-20151123:2015-11-23T10:18:03.927644+00:00 garibaldi dhcpd:
>> failover peer newc-dhcp: I move from startup to shutdown
>> dhcpd.log-20151123:2015-11-23T10:18:03.940208+00:00 garibaldi dhcpd:
>> failover peer newc-dhcp: peer moves from communications-interrupted to
>> partner-down
>
> So what version of DHCPD are you running, a (stupid) feature was
> introduced in a particular version (now regressed) to automatically
> enter partner-down on a shut down, that is the root of your problems,
> you should not be entering partner-down at all as the partner is not
> down, and then it has to go through it's recovery stage to get back
> into normal mode. Also check the init script to make sure it's not
> doing anything silly with omshell to initiate a shutdown as that will
> also trigger partner-down.
>
> Others on the list might be able to comment which version this change
> was regressed in.
>
> Steve
Hi Steve,
It?s version 4.2.6 as shipped with SLES12.
Cheers,
James
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