Update procedure
David Coulthart
davec at columbia.edu
Fri Mar 27 12:54:54 UTC 2009
On Mar 26, 2009, at 5:33 PM, David W. Hankins wrote:
> On Thu, Mar 26, 2009 at 04:18:36PM -0400, David Coulthart wrote:
>> What would the update procedure look like if you need to do an
>> upgrade from
>> 3.0.x to 4.1.x? If I upgrade one server to 4.1.x without taking
>> down the
>> second one still running 3.0.x (so I don't cause an outage for my
>> users)
>> will dhcpd recognize that they're trying to speak incompatible
>> versions of
>> the failover protocol and just refuse to talk to one another? Or
>> could
>> this result in some form of lease file corruption so I have to take
>> both
>> servers down before bringing them up on 4.1.x (causing a brief
>> outage for
>> users)?
>
> There's no risk to the lease database. Older versions would log very
> odd looking errors, newer versions more gently explain the problem.
>
> I usually recommend faulting the lease database with the 3.0->3.1+
> upgrade (because a lot of bugs throughout development would cause
> lease database inconsistency) "just to be sure," but that's up to you.
Based on this message:
https://lists.isc.org/pipermail/dhcp-users/2008-September/007051.html
faulting the lease database seems to mean moving the existing
dhcpd.leases file out of the way and allowing it to re-sync using the
failover protocol.
Are you suggesting the same thing as you did in that message -- to
fault just the secondary's database? So the procedure to upgrade
would look something like:
1) Stop old dhcpd on primary (secondary continues answering users)
2) Start new dhcpd on primary w/existing dhcpd.leases (no failover
sync will take place b/c of protocol mismatch)
3) Stop old dhcpd on secondary
4) Move dhcpd.leases on secondary out of the way
5) Start up new dhcpd on secondary w/empty dhcpd.leases (relying on
failover to sync w/primary)
If this is what you are suggesting, won't that mean that any leases
given out by the secondary b/w steps 1 & 3 are lost? If planned
properly the time b/w steps 1 & 3 should be minimal, but I just want
to make sure I'm understanding the full picture.
Thanks,
Dave Coulthart
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