Problems with pool balancing.
Erling Paulsen
erling.paulsen at uit.no
Mon May 6 11:44:22 UTC 2013
Hello,
We have two servers in failover relationship, both running
isc-dhcp42-server-4.2.4_2 on FreeBSD 8.3-RELEASE-p7 and we are having
problems with balancing the pools when pool-usage climbs into the higher
figures.
Example (numbers from logfiles at about the same timestamp):
Master: total 3905 free 1 backup 512 lts -255
"lts" is correct according to the the documentation at (free - backup)/2
= -255
Since "leases to share" is negative, the master expects the secondary
server to hand over leases!
Secondary: total 3905 free 513 backup 0 lts -256
"lts" is correct according to the the documentation at (free - backup)/2
= -256
They do seem to have the same understanding of the current lease
situatioon. But! "lts" on secondary is also negative, so it's also
expecting the master to hand over leases!
This cannot possibly end well?
This is what's in the source-code and it seems to comply with the
description:
if (p->failover_peer->i_am == primary) {
lts = (p->free_leases - p->backup_leases) / 2;
peer_lease_state = FTS_BACKUP;
/* my_lease_state = FTS_FREE; */
lq = &p->free;
} else {
lts = (p->backup_leases - p->free_leases) / 2;
peer_lease_state = FTS_FREE;
/* my_lease_state = FTS_BACKUP; */
lq = &p->backup;
}
I don't understand what can be the cause of the double-trouble negative
lts on both sides! And, btw, can someone shed a light on how the 'lq'
pointer affects the balancing?
Anyone have thoughts of what might be the culprit here?
Any information would be appreciated.
- Erling Paulsen
--
---------------------------------|sent-av|-----
Erling Paulsen, Seksjon for Infrastruktur/Nett
TEO 2.402, Universitetet i Tromsø, 9037 TROMSØ .
Kontor (+47) 77 64 64 80 Mob (+47) 91 17 64 01 ..:
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