arangodb集群重启失败

Question

我们在5台服务器上设置了一个包含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，如果它超过了其中一台服务器上的最大内存，集群将完全失败。为了避免这种情况，由于我们没有找到控制内存使用的方法，我们使用top |grep arangod命令定期观察每个节点，如果消耗太多，则重新启动节点。它通常工作得很好。但是，当我们尝试重新启动一个节点时，我们收到了如下日志：

    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)

所有的服务器都能很好地相互连接，所以这不是网络的问题。

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，并且集群不能正常工作。有人知道为什么吗？

Answer 1

引用github的讨论

请注意，命令--cluster.agent-size 5只能在第一次启动集群时使用。这是由于启动器在第一次启动时写入了不能再更改的集群配置。

因此，在您的示例中，如果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如果您希望确保在关闭两个(随机)节点时5个节点的集群处于运行状态，则代理大小=5就是所需的

如果代理未启动并运行，群集将无法工作。该机构使用RAFT协议。如果你的代理是由3个代理组成的，那么如果有两个代理宕机了，那么这个代理就是宕机了(你的集群也是如此)。如果你的代理是由5个代理组成的，那么如果两个代理宕机了，代理将会存活下来(对于你的集群也是如此)

如果你想在3台机器停机的情况下存活，那么其他的设置也是可能的

您还可以考虑对代理使用单独的计算机，例如：

用于机构

• 的
• 3台专用计算机加上用于DBServers+Coordinators的另外3台计算机(共6台计算机)，复制因子= 3

上面的设置将保留到1个代理宕机和2个DBServers宕机(因此总共3台机器宕机)