rrdtool fetch 返回 None 对象

Question

我在python中使用rrdtool库。同样的 python 脚本在一天前返回了数据，但现在它突然在生成的元组中返回了 None 对象。尚未修改 rrd 文件。返回的类型是元组，如果打印，甚至是 rrdinfo。请花一些时间研究一下。

    import sys
    import pprint
    sys.path.append('/opt/plexus-srv/rrdtool-1.4.9/lib64/python2.6/site-
    packages')
    import rrdtool
    rrd_file = sys.argv[1]
    rrd_info = rrdtool.info(rrd_file)
    data = rrdtool.fetch(rrd_file,"AVERAGE")
    print(type(data))
    pp = pprint.PrettyPrinter(indent =4)
    pp.pprint(data)
    pp.pprint(rrd_info)

输出为：

    <type 'tuple'>
('sum',)
1510142400
[(None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,), (None,)]
     {   'ds[sum].index': 0L,
    'ds[sum].last_ds': '99.3',
    'ds[sum].max': None,
    'ds[sum].min': None,
    'ds[sum].minimal_heartbeat': 120L,
    'ds[sum].type': 'GAUGE',
    'ds[sum].unknown_sec': 0L,
    'ds[sum].value': 1290.8999999999999,
    'filename': '/home/u43555766/aad/plexus/rrdsample/testing/cpu/cpu_idle.rrd',
    'header_size': 1416L,
    'last_update': 1510030543L,
    'rra[0].cdp_prep[0].unknown_datapoints': 0L,
    'rra[0].cdp_prep[0].value': None,
    'rra[0].cf': 'AVERAGE',
    'rra[0].cur_row': 49L,
    'rra[0].pdp_per_row': 1L,
    'rra[0].rows': 490L,
    'rra[0].xff': 0.5,
    'rra[1].cdp_prep[0].unknown_datapoints': 0L,
    'rra[1].cdp_prep[0].value': 198.78666666666669,
    'rra[1].cf': 'AVERAGE',
    'rra[1].cur_row': 2264L,
    'rra[1].pdp_per_row': 4L,
    'rra[1].rows': 2890L,
    'rra[1].xff': 0.5,
    'rra[2].cdp_prep[0].unknown_datapoints': 0L,
    'rra[2].cdp_prep[0].value': 198.78666666666669,
    'rra[2].cf': 'AVERAGE',
    'rra[2].cur_row': 873L,
    'rra[2].pdp_per_row': 20L,
    'rra[2].rows': 2026L,
    'rra[2].xff': 0.5,
    'rra[3].cdp_prep[0].unknown_datapoints': 0L,
    'rra[3].cdp_prep[0].value': 22058.293333333328,
    'rra[3].cf': 'AVERAGE',
    'rra[3].cur_row': 387L,
    'rra[3].pdp_per_row': 240L,
    'rra[3].rows': 754L,
    'rra[3].xff': 0.5,
    'rra[4].cdp_prep[0].unknown_datapoints': 0L,
    'rra[4].cdp_prep[0].value': 117354.74000000028,
    'rra[4].cf': 'AVERAGE',
    'rra[4].cur_row': 214L,
    'rra[4].pdp_per_row': 5760L,
    'rra[4].rows': 375L,
    'rra[4].xff': 0.5,
    'rrd_version': '0003',
    'step': 15L}

Answer 1

这个问题最明显的答案是没有要返回的数据。

您没有说明是否以及如何将数据添加到 RRD 文件。 由于您的"fetch"调用没有任何参数来指定分辨率，开始或结束，因此它可能会获得一天的默认值，现在以5分钟的分辨率结束。 您确实有一个与之匹配的 RRA，但我们无法知道其中是否有任何数据。

查看您提供的数据，您似乎在 1510142400 时间运行 fetch，但 RRD 上次更新是在大约 31 小时前的 1510030543。 可能最后一天没有数据？

尝试从命令行运行"rrdtool fetch"和"rrdtool dump"，并验证是否存储了数据，以及它们是否适合您认为的时间。 也许将其他参数传递给"fetch"以指定步骤、开始和结束。

Answer 2

我是 rrdtool 的新手，所以没有意识到我错过了收集数据的开始时间。这些文件是几天前从服务器来的。获取命令缺少"-s"时间，因此打印了无对象。将"-s"与"-96h"添加打印数据。得益于@steve船道