arangodb 集群重启失败

Question

我们在 5 个服务器上建立了一个带有 3 个代理、5 个协调器和 5 个数据库服务器的 arangodb 集群。

环境：Centos 6

我们的经验是，如果超过其中一台服务器的最大内存，集群将完全失败。 为了避免它并且由于我们没有找到控制内存使用的方法，我们使用命令top |grep arangod定期观察每个节点，如果它们消耗过多，则重新启动它们。 它通常工作正常。 但是当我们尝试重新启动一个节点时，我们收到如下日志：

    2018/03/27 15:47:31 Failed to get master URL, retrying in 5sec (All 3 servers responded with temporary failure)
    2018/03/27 15:47:31 ## Start of dbserver log
        2018-03-27T07:46:31Z [37755] WARNING {memory} It is recommended to set NUMA to interleaved.
        2018-03-27T07:46:31Z [37755] WARNING {memory} put 'numactl --interleave=all' in front of your command
        2018-03-27T07:46:31Z [37755] INFO using storage engine rocksdb
        2018-03-27T07:46:31Z [37755] INFO {cluster} Starting up with role PRIMARY
        2018-03-27T07:46:41Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 21 (9.84s). Network checks advised.
        2018-03-27T07:46:42Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 22 (10.82s). Network checks advised.
        2018-03-27T07:46:43Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 23 (11.89s). Network checks advised.
        2018-03-27T07:46:44Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 24 (13.03s). Network checks advised.
        2018-03-27T07:46:46Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 25 (14.25s). Network checks advised.
        2018-03-27T07:46:47Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 26 (15.57s). Network checks advised.
        2018-03-27T07:46:48Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 27 (16.99s). Network checks advised.
        2018-03-27T07:46:50Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 28 (18.51s). Network checks advised.
        2018-03-27T07:46:51Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 29 (20.15s). Network checks advised.
        2018-03-27T07:46:53Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 30 (21.9s). Network checks advised.
        2018-03-27T07:46:55Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 31 (23.8s). Network checks advised.
        2018-03-27T07:46:57Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 32 (25.83s). Network checks advised.
        2018-03-27T07:46:59Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 33 (28.01s). Network checks advised.
        2018-03-27T07:47:02Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 34 (30.36s). Network checks advised.
        2018-03-27T07:47:04Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 35 (32.89s). Network checks advised.
        2018-03-27T07:47:04Z [37755] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 36 (32.89s). Network checks advised.
2018/03/27 15:47:31 ## End of dbserver log
2018/03/27 15:47:32 ## Start of coordinator log
        2018-03-27T07:46:32Z [37769] WARNING {memory} It is recommended to set NUMA to interleaved.
        2018-03-27T07:46:32Z [37769] WARNING {memory} put 'numactl --interleave=all' in front of your command
        2018-03-27T07:46:32Z [37769] INFO using storage engine rocksdb
        2018-03-27T07:46:32Z [37769] INFO {cluster} Starting up with role COORDINATOR
        2018-03-27T07:46:42Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 21 (9.84s). Network checks advised.
        2018-03-27T07:46:43Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 22 (10.82s). Network checks advised.
        2018-03-27T07:46:44Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 23 (11.89s). Network checks advised.
        2018-03-27T07:46:45Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 24 (13.03s). Network checks advised.
        2018-03-27T07:46:47Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 25 (14.25s). Network checks advised.
        2018-03-27T07:46:48Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 26 (15.57s). Network checks advised.
        2018-03-27T07:46:49Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 27 (16.99s). Network checks advised.
        2018-03-27T07:46:51Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 28 (18.51s). Network checks advised.
        2018-03-27T07:46:52Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 29 (20.14s). Network checks advised.
        2018-03-27T07:46:54Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 30 (21.9s). Network checks advised.
        2018-03-27T07:46:56Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 31 (23.8s). Network checks advised.
        2018-03-27T07:46:58Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 32 (25.83s). Network checks advised.
        2018-03-27T07:47:00Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.30:8531. Unsuccessful consecutive tries: 33 (28.01s). Network checks advised.
        2018-03-27T07:47:03Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 34 (30.36s). Network checks advised.
        2018-03-27T07:47:05Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.29:8531. Unsuccessful consecutive tries: 35 (32.89s). Network checks advised.
        2018-03-27T07:47:05Z [37769] INFO {agencycomm} Flaky agency communication to http+tcp://65.18.27.28:8531. Unsuccessful consecutive tries: 36 (32.89s). Network checks advised.
2018/03/27 15:47:32 ## End of coordinator log
2018/03/27 15:47:46 Failed to get master URL, retrying in 5sec (All 3 servers responded with temporary failure)

所有服务器之间都可以ping通，所以不是网络问题。

就在我写这个问题并收集日志信息时，集群成功重启。 这有点奇怪。 现在 2 个节点将日志打印为

updated cluster config does not contain myself. rejecting

现在显示集合需要很长时间，并且集群无法正常工作。 有人知道为什么吗？

Answer 1

[引用github讨论]

请注意，只有在第一次启动集群时才必须使用命令 --cluster.agency-size 5。 这是因为 starter 在第一次启动时写入了无法再更改的集群配置。

因此，在您的情况下，如果您需要在其他节点中添加更多代理，则必须在每个新节点上使用 --cluster.start-agent true 如果您想确保在关闭时您的 5 个节点集群正在运行两个（随机）节点，那么您需要一个代理大小 = 5

如果代理未启动并运行，集群将无法工作。 该机构使用 RAFT 协议。 如果您的代理由 3 个代理组成，那么如果有两个代理停止运行，则代理停止运行（对于您的集群也是如此）。 如果您的代理由 5 个代理组成，那么如果两个代理宕机，代理将继续存在（对于您的集群也是如此）

如果你想生存到 3 台机器停机，那么其他设置是可能的

您还可以考虑为代理使用单独的机器，例如：

• 3台机构专用机器
• 加上额外的 3 台用于 DBServers+Coordinators 的机器（总共 6 台机器），复制因子 = 3

上述设置将在 1 个 Agent 宕机和 2 个 DBServers 宕机的情况下继续存在（因此总共有 3 台机器宕机）