cacti监控流量1000M不准确的问题
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cacti监控网络边界流量的问题，当流量超过100M时不准确，网上查了很多资料都说是不支持64位采集或者net-snmp版本过低的问题，但经过测试我的情况不属于上述两者。
* use 64 bit snmp counters if your device supports it (probably needs snmp v2 or above)
* use shorter polling interval, for example 1 minute, but note that you need to change more than just the polling interval (graph, rra and so on)
i'm using 1min polling intervals for 32bit counters on 1 gbit interfaces and a different graph+datasource setup, and this works fine.
it also gives better precition for the last couple of ours (1min intervals instead of 5min).
后发现cacti 的官方论坛里有这样的回复：
the problem is that a 32 bit snmp counter overflows between the 5 min polling intevals that is used by default.
you have two options:* use 64 bit snmp counters if your device supports it (probably needs snmp v2 or above)
* use shorter polling interval, for example 1 minute, but note that you need to change more than just the polling interval (graph, rra and so on)
i'm using 1min polling intervals for 32bit counters on 1 gbit interfaces and a different graph+datasource setup, and this works fine.
it also gives better precition for the last couple of ours (1min intervals instead of 5min).
check the forums, there should be some info about this.
原来，把cacit的poller时间改成1分钟，可以解决这个问题，于是：
1.将cacti的poller设置中Poller Interval和Cron Interval两项改为Every Minute
2.安装spine，并将cacti的poller类型修改为spine（原来为cmd.php）
3.修改/etc/cron.d/cacti 计划任务文件：*/1 * * * * cacti php /var/www/cacti/poller.php &>/dev/null（原来为5分钟）
重新添加设备，监控流量正常。如果原来已经有设备和图形，则须将cacti/rra目录下的rrd文件删除让系统重新生成文件。
