Ao analisar os logs do Cacti notei várias entradas com o seguinte conteúdo:

RECACHE STATS: RecacheTime:0.8475 HostsRecached:1
PCOMMAND: Poller[0] Host[67] WARNING: Recache Event Detected for Host
SYSTEM STATS: Time:12.0107 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:947
CMDPHP: Poller[0] ASSERT: '100321047<' failed. Recaching host '192.0.2.1', \
data query #1
RECACHE STATS: RecacheTime:0.8652 HostsRecached:1
PCOMMAND: Poller[0] Host[67] WARNING: Recache Event Detected for Host
SYSTEM STATS: Time:10.9035 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
CMDPHP: Poller[0] ASSERT: '100315052<' failed. Recaching host '192.0.2.1', \
data query #1
RECACHE STATS: RecacheTime:0.8512 HostsRecached:1
PCOMMAND: Poller[0] Host[67] WARNING: Recache Event Detected for Host
SYSTEM STATS: Time:10.9751 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
CMDPHP: Poller[0] ASSERT: '100308942<' failed. Recaching host '192.0.2.1', \
data query #1
RECACHE STATS: RecacheTime:0.8617 HostsRecached:1
PCOMMAND: Poller[0] Host[67] WARNING: Recache Event Detected for Host
SYSTEM STATS: Time:9.8851 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
CMDPHP: Poller[0] ASSERT: '100303042<' failed. Recaching host '192.0.2.1', \
data query #1
RECACHE STATS: RecacheTime:0.8479 HostsRecached:1
PCOMMAND: Poller[0] Host[67] WARNING: Recache Event Detected for Host
SYSTEM STATS: Time:10.9099 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
CMDPHP: Poller[0] ASSERT: '100296943<' failed. Recaching host '192.0.2.1', \
data query #1

Isso significa que o poller está marcando o host em questão para reindexação, a causa é que possivelmente algum campo SNMP não está coincidindo com os índices atuais. Entretanto, os logs vão se repetindo e o Cacti não consegue resolver o problema sozinho.

Para corrigir manualmente, basta seguir a seguinte documentação:

http://docs.cacti.net/manual:087:6_reference.4_cli_script.2_reindex_host...

Ou então (mais rápido e mais amigável para quem não é acostumado a linha de comando), execute o seguinte (pela interface gráfica do próprio Cacti):

Console > System Utilities > Rebuild Poller Cache

Após alguns minutos notará que os logs não apresentam mais o problema.

SYSTEM STATS: Time:11.6298 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.8974 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.9775 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.9092 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.9644 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.8743 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.9095 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980
SYSTEM STATS: Time:10.8851 Method:cmd.php Processes:4 Threads:N/A Hosts:77 \
HostsPerProcess:20 DataSources:1845 RRDsProcessed:980