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Today's Topics:

   1. Re: DHCP pair messed up, second one only running cant get
      primary up. (Simon Hobson)
   2. Re: DHCP pair messed up, second one only running cant get
      primary up. (Rob Morin)
   3. RE: DHCP pair messed up, second one only running cant get
      primary up. (Rob Morin)


----------------------------------------------------------------------

Message: 1
Date: Fri, 13 Jan 2017 20:30:59 +0000
From: Simon Hobson <dh...@thehobsons.co.uk>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP pair messed up, second one only running cant get
        primary up.
Message-ID: <70be0d13-efa4-4c30-9275-d44a0d2cf...@thehobsons.co.uk>
Content-Type: text/plain; charset=iso-8859-1

Rob Morin <rmo...@datavalet.com> wrote:

> Also the dhcpd.leases files grow too big for the /ramdisk, so we are each 10 
> mins catting /dev/null into /ramdisk/dhcpd.lease! file to save space.

I can't help with the other problems, but pray you don't have to stop the DHCP 
server at any time before it's re-written the compacted leases file ! Losing 
the leases file is "bad" in a big way.

I can't help with the specific problem, but I would suggest that if you 
lengthen the lease time (by a considerable amount) it will dramatically reduce 
the rate of growth of the leases file. With a lease length of 20 minutes, 
you'll have a renewal every 10 minutes (roughly) - so that's 6 lease updates to 
the leases file per hour !

For example, if you were to increase the lease time to (say) 4 hours, then your 
leases file would contain one record per lease (in practical terms, every 
address in your pools) plus one update for roughly 1/2 the active clients.

So your lease file size will change from total of IP ranges + 6x number of 
active clients, to total of IP ranges plus 1/2 the active clients.


Is there a reason for having such short leases ? It's quite short, longer 
leases bring much stability and much more leeway in dealing with DHCPO service 
issues !

Also, for consideration, you can have more than 2 servers in failover - but 
only 2 per pool. So it's possible to have (say) 3 servers sharing the load as 
A+B, B+C, and C+A. More complexity, but more scope for server failure without 
losing DHCP service - and more load sharing. Of course, you can also just split 
pools across an even number of servers as A+B, C+D, etc.



------------------------------

Message: 2
Date: Fri, 13 Jan 2017 21:39:01 -0500
From: Rob Morin <rmo...@datavalet.com>
To: Simon Hobson <dh...@thehobsons.co.uk>, Users of ISC DHCP
        <dhcp-users@lists.isc.org>
Subject: Re: DHCP pair messed up, second one only running cant get
        primary up.
Message-ID: <hagtsfbg05u10i9g8sutthd2.1484361541...@email.android.com>
Content-Type: text/plain; charset="utf-8"

Sorry I had a typo in my email we cat /dev/null into dhcp. leases~ file not the 
active file?


Sent from Samsung Mobile

<div>-------- Original message --------</div><div>From: Simon Hobson 
<dh...@thehobsons.co.uk> </div><div>Date:01-13-2017  3:30 PM  (GMT-05:00) 
</div><div>To: Users of ISC DHCP <dhcp-users@lists.isc.org> </div><div>Subject: 
Re: DHCP pair messed up, second one only running cant get primary up. 
</div><div>
</div>Rob Morin <rmo...@datavalet.com> wrote:

> Also the dhcpd.leases files grow too big for the /ramdisk, so we are each 10 
> mins catting /dev/null into /ramdisk/dhcpd.lease! file to save space.

I can't help with the other problems, but pray you don't have to stop the DHCP 
server at any time before it's re-written the compacted leases file ! Losing 
the leases file is "bad" in a big way.

I can't help with the specific problem, but I would suggest that if you 
lengthen the lease time (by a considerable amount) it will dramatically reduce 
the rate of growth of the leases file. With a lease length of 20 minutes, 
you'll have a renewal every 10 minutes (roughly) - so that's 6 lease updates to 
the leases file per hour !

For example, if you were to increase the lease time to (say) 4 hours, then your 
leases file would contain one record per lease (in practical terms, every 
address in your pools) plus one update for roughly 1/2 the active clients.

So your lease file size will change from total of IP ranges + 6x number of 
active clients, to total of IP ranges plus 1/2 the active clients.


Is there a reason for having such short leases ? It's quite short, longer 
leases bring much stability and much more leeway in dealing with DHCPO service 
issues !

Also, for consideration, you can have more than 2 servers in failover - but 
only 2 per pool. So it's possible to have (say) 3 servers sharing the load as 
A+B, B+C, and C+A. More complexity, but more scope for server failure without 
losing DHCP service - and more load sharing. Of course, you can also just split 
pools across an even number of servers as A+B, C+D, etc.

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dhcp-users@lists.isc.org
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------------------------------

Message: 3
Date: Sat, 14 Jan 2017 07:23:22 +0000
From: Rob Morin <rmo...@datavalet.com>
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: RE: DHCP pair messed up, second one only running cant get
        primary up.
Message-ID:
        
<sn2pr01mb1983ac12484ffb8aa74e9f3dca...@sn2pr01mb1983.prod.exchangelabs.com>
        
Content-Type: text/plain; charset="iso-8859-1"

Our lease time is governed by our client, which is huge. That cannot be 
changed. :)

Rob Morin
Gestionnaire des syst?mes | Senior System administrator
 
T 514 385-4448 #174                 DATAVALET.COM
 
5275, chemin Queen-Mary, Montr?al (Qu?bec) H3W 1Y3 Canada
 
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-----Original Message-----
From: dhcp-users [mailto:dhcp-users-boun...@lists.isc.org] On Behalf Of Simon 
Hobson
Sent: Friday, January 13, 2017 3:31 PM
To: Users of ISC DHCP <dhcp-users@lists.isc.org>
Subject: Re: DHCP pair messed up, second one only running cant get primary up.

Rob Morin <rmo...@datavalet.com> wrote:

> Also the dhcpd.leases files grow too big for the /ramdisk, so we are each 10 
> mins catting /dev/null into /ramdisk/dhcpd.lease! file to save space.

I can't help with the other problems, but pray you don't have to stop the DHCP 
server at any time before it's re-written the compacted leases file ! Losing 
the leases file is "bad" in a big way.

I can't help with the specific problem, but I would suggest that if you 
lengthen the lease time (by a considerable amount) it will dramatically reduce 
the rate of growth of the leases file. With a lease length of 20 minutes, 
you'll have a renewal every 10 minutes (roughly) - so that's 6 lease updates to 
the leases file per hour !

For example, if you were to increase the lease time to (say) 4 hours, then your 
leases file would contain one record per lease (in practical terms, every 
address in your pools) plus one update for roughly 1/2 the active clients.

So your lease file size will change from total of IP ranges + 6x number of 
active clients, to total of IP ranges plus 1/2 the active clients.


Is there a reason for having such short leases ? It's quite short, longer 
leases bring much stability and much more leeway in dealing with DHCPO service 
issues !

Also, for consideration, you can have more than 2 servers in failover - but 
only 2 per pool. So it's possible to have (say) 3 servers sharing the load as 
A+B, B+C, and C+A. More complexity, but more scope for server failure without 
losing DHCP service - and more load sharing. Of course, you can also just split 
pools across an even number of servers as A+B, C+D, etc.

_______________________________________________
dhcp-users mailing list
dhcp-users@lists.isc.org
https://lists.isc.org/mailman/listinfo/dhcp-users


------------------------------

Subject: Digest Footer

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------------------------------

End of dhcp-users Digest, Vol 99, Issue 6
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